Scientific American Supplement, No. 598, June 18, 1887
by
Various
Part 1 out of 2
Produced by by Don Kretz, Juliet Sutherland, Charles Franks and the
DP Team
[Illustration]
SCIENTIFIC AMERICAN SUPPLEMENT NO. 598
NEW YORK, JUNE 18, 1887
Scientific American Supplement. Vol. XXIII, No. 598.
Scientific American established 1845
Scientific American Supplement, $5 a year.
Scientific American and Supplement, $7 a year.
* * * * *
TABLE OF CONTENTS.
I. BOTANY.--The Brazil Nut.--The botanical position, appearance,
etc., and general features of the tree and plant.--1 illustration.
II. DECORATIVE ART.--Decoration.--The study of ornaments.--By
Miss MARIE R. GARESCHE.--The principles of ornament and
relations between nature and art; ancient and mediaeval art
contrasted.--1 illustration.
III. ELECTRICITY.--Electric Registering Apparatus for Meteorological
Instruments.--Grime's telemareograph described; an apparatus
giving distant registrations of tidal phenomena.--2 illustrations.
The Montaud Accumulator.--Full account of construction and
power of this recent battery.--4 illustrations.
IV. ENGINEERING.--Belt Joints.--A new cement, the "Hercules
glue," and its adaptation for cementing belt joints.
V. MINERALOGY.--Precious Stones of the United States.--A review
of Mr. G.F. KUNZ'S recent report on this subject.
VI. MISCELLANEOUS.--A Clinical Lesson at "La Salpetriere."--A
portraiture picture by M. ANDRE BROUILLET, of a clinic.--2
illustrations.
Inauguration of the statue of Denis Papin.--The statue to Papin
erected in Paris by popular subscription.--1 illustration.
The Action of the Magnet in Hypnosis.--The nullity of the action
of the magnet disclosed.
To Find the Day of the Week for any Year.--A new method devised
by Lewis Carroll.
VII. NAVAL ENGINEERING.--Some Recent High Speed Twin
Screws.--By E.A. LINNINGTON.--An important paper on the subject
of screw propulsion.--6 illustrations.
The Havre Maritime Exhibition.--Notes on the recently opened
exhibition of ships and naval appliances at Havre.--1 illustration.
The New German Corvette Greif.--A recent addition to the German
fleet illustrated and described.--1 illustration.
The Steamship Great Eastern.--A plea for the mammoth
steamer.--Probabilities of her future usefulness.
Twin Screw Torpedo Boat.--The new sea-going vessel built by
Yarrow & Co. for the Italian government.--Her extraordinary
speed.
VIII. ORDNANCE.--Our Coast Defenses.--An interesting summary
by Gen. H.L. ABBOTT of our means for defending our coasts.
The New Krupp Guns.--The dimensions of the largest guns in
the world, now in process of construction at Essen.--2 illustrations.
IX. PHYSICS.--Colors of Thin Plates.--Report of a recent lecture by
Lord Rayleigh.
X. TECHNOLOGY.--Recent Advances in Sewing Machines.--By
JOHN W. URQUHART.--A recent lecture before the Society of
Arts of London, giving an exhaustive review of the subject.--15
illustrations.
* * * * *
THE HAVRE MARITIME EXHIBITION.
The Havre Maritime Exhibition opened on the 7th of May.
Will this exhibition awaken general interest, or will it prove a local
affair simply? This is a secret of the weeks that are to follow.
Should nothing chance to discourage the general interest that surrounds
Havre, to dampen the enthusiasm of the public, or to act to the prejudice
of the exhibitors, whose very evident desire is to show nothing but
remarkable products in every line, the International Maritime Exhibition
will prove a great success.
[Illustration: THE INTERNATIONAL MARINE EXHIBITION AT HAVRE.--THE
PRINCIPAL ENTRANCE.]
The people of Havre have two points of comparison that more particularly
concern themselves: Their Maritime Exhibition of 1868, which, as far as
exhibition goes, was a complete success, is the first. The financial
results of it were not brilliant, but that was due to certain reasons upon
which it is not necessary to dwell. On the contrary, the Rouen Exhibition
of 1884 proved profitable.
The Havre Exhibition, under able management, can have only a like good
fortune. It must be said that the people of Havre would be deeply
humiliated should it prove otherwise.
A very appropriate location was selected for the Exhibition, in the busiest
quarter of the center of the city. Its circumference embraces one of the
finest docks of the port--the Commerce Dock, thus named because it could
not be finished (in 1827) except by the financial co-operation of the
shipowners and merchants of the city. For the purposes of the Exhibition,
this dock is now temporarily closed to navigation.
In the various structures, wood has been exclusively employed. The main
building, which alone has a monumental character, is Arabic in style, and
is situated in the center of Gambetta Place, over Paris Street, which here
becomes a tunnel. Two facades overlook the ends of this tunnel. A third
facade, which is much longer, fronts Commerce Dock.
The edifice is surmounted by a spherical cupola that serves as a base to a
semaphore provided with masts and rigging. On each side of the sphere there
are two pendent beacons. Wide glazed bays open in the external facades, and
allow the eye to wander to the south through Paris Street as far as to the
outer port, to the summits of Floride, and to see beyond this point the bay
of La Seine, Honfleur, and the coast of Grace. To the north, the most
limited view has for perspective the City Hall, its garden, and the
charming coast of Ingonville.
The principal facade, that which fronts Commerce Dock, from which it is
separated solely by a garden laid out on Mature Place, is the most
attractive and most ornamented. Here are located the restaurants, the
cafes, the music pavilion, and a few other light structures.
Internally, this portion of the Exhibition comprises a vast entertainment
hall, brilliantly and artistically decorated with tympans representing the
three principal ports of commerce--Havre, Bordeaux, and Marseilles--and
with pictures by the best marine painters. It is lighted by an immense
stained glass window which fronts Commerce Dock and the garden, and which
lets in a flood of soft light.
The galleries to the right and left, over Paris Street, are reserved for
the exhibitions of the ministers of state and of the large public
departments, and for models, specimens, plans, and drawings of war and
merchant vessels, and of pleasure boats, and for plans of port, roadstead,
and river works.
Two endless galleries run to the north and south of Commerce Dock, parallel
with Orleans Wharf on the one hand and Lamblardie Wharf on the other.
The northern gallery is connected by a foot bridge with the annex of
Commerce Place, where is located the colonial exhibition, the center of
which is occupied by a Cambodian pavilion, in which are brought together
the products of Indo-China and Algeria. For half of their extent, the two
galleries are separated from the dock by a promenade provided with seats
and covered with a roof. On this promenade, it became necessary to make
room for certain belated exhibitors whose products are not affected by the
open air.
In Commerce Dock are to be seen, floating, specimens of every ancient and
modern naval construction, French and foreign, among which are the state
convette Favorite and an English three-master converted into a cafe boat.
We find here, too, the giant and prehistoric oak of the Rhine, on board of
the Drysphore.
Commerce Dock is divided into two parts by a foot bridge, which allows the
visitors to pass from one side to the other without being compelled to
tiresomely retrace their steps.
The main entrance to the Exhibition is opposite the portico of the theater,
on Gambetta Place. A second entrance is found on Commerce Place in the
colonies annex. The others, near the center, are on Orleans Wharf, opposite
Edward Larue Street, and on Lamblardie Wharf, opposite Hospital Street and
opposite Saint Louis Street.
The garden of the Exhibition and the galleries that surround it are
illuminated at night by the electric light.--_L'Illustration._
* * * * *
OUR COAST DEFENSES.
General H.L. Abbott delivered a lecture before the Academy of Sciences in
New York, on the evening of March 21, a summary of which is given by the
_Herald_ as follows:
According to General Abbott, the country needs for its coast defenses:
Heavy guns;
Armor-clad casemates;
Disappearing gun carriages in earthworks;
Heavy mortars;
Submarine mines or fixed torpedoes; and
Fish torpedoes.
The lecturer said that this nation may be attacked in four ways: First, by
fleet and army combined, as in our revolutionary war; second, by blockading
the entrances to all our ports; third, by bombardment of our seaport cities
from a long distance; fourth, by a fleet forcing its way into our harbors,
and making a direct attack or levying tribute on our people.
The first is not now greatly to be feared. We are too distant from great
powers, and too strong on land.
The second should be met by the navy, and is, therefore, outside a
discussion of coast defenses.
The third is not probable, though it may be possible. The extreme range of
10 miles for heavy guns cannot be obtained from shipboard, and as an
elevation of only 15 deg. or 16 deg. can be given, not over 5 to 6 miles range is
attainable.
The fourth is the one which is possible, probable, even certain--if we have
war before we have better defenses.
The race between guns and armor began about thirty years ago, and there has
been more development in ships and guns in that time than in the two
hundred preceding years. The jump has been from the 7 in. rifle as the
largest piece to the 110 ton Armstrong; in armor, from 41/2 in. of iron to
the Inflexible with 22 in. of steel plating. The new Armstrong gun of 110
tons, tried only recently, with 850 pounds of powder and an 1,800 pound
shot can pierce all the targets, and so far guns have the victory over
armor. This gun developed 57,000 foot tons of energy, and will probably
reach 62,000. Imagine the Egyptian needle in Central Park, shod on its apex
with hard steel, dropped point downward from the height of Trinity steeple;
it weighs 225 tons, and it would strike with just about the effect of one
of the 110 ton gun's projectiles. Two of these guns are ready for the
ironclad Benbow, and the Italians have several equally powerful of 119 tons
from Herr Krupp. The most powerful gun in the United States, the 15 in. or
the 12 in. rifle, has a muzzle energy of 3,800 foot tons.
Ships like the Inflexible are the most powerful afloat. A steel water-tight
deck extends across the ship, and she has 135 water-tight compartments. Her
guns and engines amidships have a protection of 24 in. of armor, and
amidships she has a citadel carrying two revolving turrets, each containing
two 80 ton guns. Her turret armor is 18 in. thick. She can make 14 knots,
and she has cost $3,500,000. But she has a low freeboard, and the guns,
therefore, get no plunging fire.
The French ship Meta has her heaviest guns mounted _en barbette_, high
above the water line, giving a splendid plunging fire.
Either of these ships could enter any of our harbors and hold us at her
mercy.
The entrance to the harbor of Alexandria, Egypt, is about 5 miles across.
At the time of the bombardment the protecting fortifications were situated
at the east end, in the center, and at the west end. On the west there were
mounted 20 modern guns of great size and power, and there were 7 others at
the east end.
Although the Egyptians fought bravely, they did very little harm to the
English fleet, while on the second day the defense was silenced altogether.
Following the bombardment--as in Paris--came the reign of mob law, doing
more harm than the shells had done; and it is a possibility that every such
bombardment would be followed by such an overthrow--at least temporary--of
all forms of law and order.
The ships that had silenced the Alexandria batteries--which had 27 heavy
guns more than we have--could reach our coasts in 10 or 12 days, and we
would have nothing to meet them.
Armor-clad casemates are beginning to take the place of masonry. A
tremendous thickness of masonry is built up to the very embrasures for the
guns in the steel-clad turrets. This (the Gruson) system has been adopted
by Belgium, Holland, Germany, Austria, and Italy.
In 1882 England had 434 heavy modern guns behind armored shore batteries;
besides these at home, she had 92 in her colonies, of which 13 were in
Halifax and 11 in Bermuda--for our express benefit.
What we have are brick and stone casemates and earthworks. A sample granite
casemate, with iron-lined embrasure, was built at Fortress Monroe, and 8
shots were fired at it from a 12 in. rifle converted from an old 15 in.
smooth bore. This gun develops only 3,800 foot tons of energy--a mere
nothing compared with the 62,000 foot tons of the English and German 110
ton guns.
General Abbott showed most conclusive proof of the worthlessness of masonry
forts in pictures showing the effect of the shots. The massive 8 feet
thickness of granite was pierced and battered till it looked like a ruin.
Not a man inside would have been left alive.
He also showed a "disappearing" gun in an earthwork, the gun recoiling
below the level of the parapet and being run up to a firing position by a
counterweight. In 1878 Congress stopped all appropriations for defenses,
and nothing had been done since.
General Abbott said that we needed submarine mines or fixed torpedoes,
which should be thickly interspersed about the channel and be exploded by
an electric battery on shore. To prevent these torpedoes from being
exploded by the enemy, the surface over them should be covered by plenty of
guns. Heavy guns and mortars were needed to resist attacks by heavy
iron-clads. Movable torpedoes were valuable, but only as an auxiliary--a
very minor auxiliary--compared with submarine mines. We should be cautious
not to infer that torpedoes made a satisfactory defense alone, as they must
be protected by large and small guns, and they form only a part of the
chain of general defenses.
* * * * *
THE STEAMSHIP GREAT EASTERN.
[Footnote: See Engraving in SUPPLEMENT NO. 584.]
The history of the Great Eastern is full of surprises. It is always that
which is most unlikely to happen to her which occurs. Not long since we
recorded her sale by auction in Liverpool for L26,000. It was stated that
her purchasers were going to fit her out for the Australian trade, and that
she would at once be sent from Dublin to Glasgow to be fitted with new
engines and boilers, and to undergo thorough renovation. Lord Ravensworth,
in his address to the Institution of Naval Architects, spoke recently of
the bright future before her in that Australian trade for which she was
specially built. Yet at this moment the Great Eastern is lying in her old
berth in the Sloyne at Liverpool, and unless something else at present
quite unforeseen takes place, she will once more play the undignified part
of a floating music hall. It seems that although she was certainly sold, as
we have stated, the transaction was not completed. Her owners then cast
about for the next highest bidder, who at once took her. He is, we
understand, a Manchester cotton spinner, and he paid L25,500 for her. It is
no secret that Messrs. Lewis made a considerable sum out of the ship last
year, and the knowledge of this fact has no doubt induced her present owner
to follow their example. The ship left Dublin on Sunday, April 3, under her
own steam and in tow of two Liverpool tugs, the Brilliant Star and the
Wrestler, and arrived in the Mersey without accident on Monday, after a
passage of only thirteen hours. Mr. Reeves, formerly her chief officer, has
been made captain. Mr. Jackson is still chief engineer. We cannot at
present explain the fact that she went more than twice as fast as she has
done recently, her engines making as many as 36 revolutions a minute, save
on the assumption that while lying at Dublin much of the enormous growth of
seaweed on her bottom died off, as will sometimes happen as a result of
change of water. Her engines and boilers, too, have had a good overhaul by
Mr. Jackson, and this may account in part for this improvement. It is much
to be regretted that the scheme of using the ship for her legitimate
purpose has not been carried out. It is not, however, yet too late. The
Great Eastern was not a success in Dublin, for one reason, that a beer and
spirit license could not be obtained for her. It is said that notice has
been given at the Birkenhead police court that any application for a
license of a similar kind will be opposed. Whether the ship will be as
popular a resort without as she was with a license, we cannot pretend to
say; and we may add that all our predilections are against her degradation
to the status of a floating music hall. The greater her failure as such,
the greater the chance of her being put to a better use; and it may help to
that desirable end if we say here something concerning the way in which she
could be rendered a commercial success as a trader.
It may be taken as proved that the present value of the ship is about
L26,000. Mr. De Mattos gave, we understand, L27,000 for her, and he bought
her by auction. The last sale gives nearly the same figures. If we assume
that there are 10,000 tons of iron in her, we may also assume that if
broken up it would not fetch more than L3 a ton at present rates; but even
if we say L4, we have as a total but L40,000. To break the ship up would be
a herculean task; we very much doubt if it could be done for the difference
between L26,000 and L40,000; her engines would only sell for old iron,
being entirely worthless for any other place than the foundry once they
were taken out of her; as for her boilers, the less said about them the
better. In one word, she would not pay to break up. On the other hand, by a
comparatively moderate further outlay, she might be made the finest trading
ship afloat. There are two harbors at all events into which she can always
get, namely, Milford and Sydney. There are others, of course, but these
will do; and the ship could trade between these two ports. By taking out
her paddle engines, she would be relieved of a weight of 850 tons. The
removal of her paddle engine boilers would further lighten her, and would
give in addition an enormous stowage space. By using her both as a cargo
and a passenger ship, the whole of the upper portion could be utilized for
emigrants, let us say, and the lower decks for cargo, of which she could
carry nearly, if not quite, 20,000 tons. She would possess the great
advantage that, notwithstanding she was a cargo ship, she would be nearly,
if not quite, as fast as any, save a few of the most recent additions to
the Australian fleet. There is every reason to believe that she has been
driven at 14 knots by about 6,000 horse power. We are inclined to think
that the power has been overstated, and we have it on good authority that
she has more than once attained a speed of 15 knots. Let us assume,
however, that her speed is to be 13 knots, or about fifteen miles an hour.
Assuming the power required to vary as the cube of the speed, if 6,000
horsepower gave 14 knots, then about 4,800 would give 13 knots--say 5,000
horse power. Now, good compound engines of this power ought not to burn
more than 2 lb. per horse per hour, or say 4.5 tons per hour, or 108 tons a
day. Allowing the trip to Australia to take forty days, we have 4,320 tons
of coal--say 5,000 tons for the trip. The Etruria burns about this quantity
in the run to New York and back. For each ton of coal burned in the Great
Eastern about 15,000 tons of cargo and 3,000 passengers could be moved
about 3-1/3 miles. There is, we need hardly say, nothing afloat which can
compare in economy of fuel with this. Taken on another basis, we may
compare her with an ordinary cargo boat. In such a vessel about 3,000 tons
of grain can be moved at 9 knots an hour for 600 horse power--that is 5
tons of cargo per horse power. Reducing the speed of the Great Eastern to 9
knots and about 2,000 horse power, we have 9 tons of cargo moved at 9 knots
per horse power; so that in the relation of coal burned to cargo moved she
would be nearly twice as economical as any other vessel afloat.
The important question is, What would the necessary alterations cost? Much,
of course, would depend on what was done. A very large part of the present
screw engines could be used. For example, the crank shaft, some 2 feet in
diameter, is a splendid job, and no difficulty need be met with in working
in nearly the whole of the present framing. If the engines were only to be
compound, two of the existing cylinders might be left where they are, two
high-pressure cylinders being substituted for the others. If triple
expansion were adopted, then new engines would be wanted, but the present
crank and screw shafts would answer perfectly. The present screw would have
to be removed and one of smaller diameter and less pitch put in its place.
All things considered, we believe that for about L75,000 the Great Eastern
could be entirely renovated and remodeled inside. Her owners would then
have for, say, L100,000 a ship without a rival. Her freights might be cut
so low that she would always have cargo enough, and her speed and moderate
fares ought to attract plenty of passengers. Sum up the matter how we may,
there appears to be a good case for further investigation and inquiry as to
the prospects of success for such a ship in the Australian trade, and the
opinion of merchants and others in Melbourne and Sydney ought to be
obtained. Something would be gained even if the opinions of unprejudiced
experts were adverse. We might then rest content to regard the ship as an
utter failure, and not object to see her sunk and filled with concrete to
play the part of a breakwater. Until, however, such an opinion has been
expressed after full discussion, we must continue to regard the ship as fit
for something better than a music hall and dancing saloon.--_The Engineer_.
* * * * *
THE NEW GERMAN CORVETTE GREIF.
Our cut represents the corvette Greif--the latest addition to the German
fleet--on its trial trip, March 10. As other naval powers, especially
England and France, have lately built corvettes and cruisers which can
travel from 17 to 18 knots, while the fastest German boats, Blitz and
Pfeil, can make only 16 knots an hour, the chief of the Imperial Admiralty
decided to construct a corvette which should be the fastest vessel in the
world. The order was given to the ship and engine corporation "Germania,"
of Berlin and Keil, in April, 1885, the requirements being that the engines
should generate 5,400 h.p., and that the vessel, when loaded, should have a
speed of 19 knots, a point which has never been reached by any boat of its
size. The hull is made of the best German steel of Krupp's manufacture, and
measures 318 ft. in length at the water line, with a breadth of beam of 33
ft., the depth from keel to deck being 22 ft. It draws about 11 ft., and
has a displacement of 2,000 tons.
As the vessel is to be used principally as a dispatch boat and for
reconnoitering, and as--on account of its great speed--it will not be
obliged to come into conflict with larger and stronger men-of-war, no great
preparations for protection were needed, nor was it necessary that it
should be heavily armed, all available room being devoted to the engines,
boilers, and the storing of coal; these occupy more than half the length of
the vessel, leaving only space enough for the accommodation of the officers
and crew at the ends. The armament consists of five Hotchkiss revolving
guns on each side, and a 4 in. gun at each end, the latter being so
arranged that each one can sweep half the horizon.
The keel was laid in August, 1885, and the ship was launched July 29,
1886, on which occasion it was christened Greif. On the trial trip it was
found that the slender shape of the vessel adapted it for the development
of a very high rate of speed under favorable conditions, when it can make
at least 22 knots an hour, so that the speed of 19 knots an hour guaranteed
by the builders can certainly be reached, even when traveling at a
disadvantage. In spite of its great length, the Greif can be easily
maneuvered. When moving forward at full speed, it can be made to describe a
circle by proper manipulation of the rudder, and by turning one screw
forward and the other backward, the ship can be turned in a channel of its
own length.
[Illustration: THE NEW GERMAN WAR STEAMER GREIF.]
A large and rapid cruiser, also for the German navy, is being built by the
corporation "Germania". This vessel is of about the same length as the
Greif, has more than double its displacement, and will make 18 knots an
hour, an unusual rate of speed for a vessel of its class. It will be
launched by the last of the summer or early in the fall.
* * * * *
TWIN SCREW TORPEDO BOAT.
We give several illustrations of a sea going twin screw torpedo boat lately
built for the Italian government by Messrs. Yarrow & Co., of Poplar. The
vessel in question is 140 ft. long by 14 ft. wide, and her displacement
approaches close on 100 tons. The engines are of the compound surface
condensing type ordinarily fitted by this firm in their torpedo boats,
excepting where triple compounds are fitted. The general arrangement is
shown by the sectional plan. As will be noticed, there are two boilers, one
before and the other aft of the engines, and either boiler is arranged to
supply either or both the engines. Yarrow's patent water tight ash pans are
fitted to each boiler, to prevent the fire being extinguished by a sudden
influx of water into the stokehold. There is an independent centrifugal
pumping engine arranged to take its suction from any compartment of the
boat. There are also steam ejectors and hand pumps to each compartment.
These compartments are very numerous, as the space is much subdivided, both
from considerations of strength and safety. Bow and stern rudders are
fitted, each having independent steam steering gear, but both rudders can
be worked in unison, or they can be immediately changed to hand gear when
necessary. The accommodation is very good for a vessel of this class.
Officers' and petty officers' cabins are aft, while the crew is berthed
forward.
[Illustration: TWIN SCREW TORPEDO BOAT FOR THE ITALIAN GOVERNMENT.]
The armament consists of two bow tubes built in the boat. There are two
turntables, as shown in the illustrations, each fitted with two torpedo
tubes. These, it will be noticed, are not arranged parallel to each other,
but lie at a small angle, so that if both torpedoes are ejected at once,
they will take a somewhat divergent course. Messrs. Yarrow have introduced
this plan in order to give a better chance for one of the torpedoes to hit
the vessel attacked. There are two quick firing three pounder guns on deck,
and there is a powerful search light, the dynamo and engine being placed in
the galley compartment.
We believe, says _Engineering_, this torpedo boat, together with a sister
vessel, built also for the Italian government, are the fastest vessels of
their class yet tried, and it is certain that the British Navy does not yet
possess a craft to equal them. It is an extraordinary and lamentable fact
that Great Britain, which claims to be the foremost naval power in the
world, has always been behind the times in the matter of torpedo boats.
The official trial of this boat was recently made in the Lower Hope in
rough weather. The following is a copy of the official record of the six
runs on the measured mile:
Boiler | Receiver | |Revolutions | | |Second
Pressure.| Pressure.| Vacuum. | per Minute.| Speed.| Means.| Means.
-------------+----------+---------+------------+-------+-------+------
|lb. | lb. | in. | | | |
1 | 130 | 32 | 28 | 373 | 22.641| |
| | | | | | 24.956|
2 | 130 | 32 | 28 | 372.7 | 27.272| | 24.992
| | | | | | 25.028|
3 | 130 | 32 | 28 | 372 | 22.784| | 25.028
| | | | | | 25.028|
4 | 130 | 32 | 28 | 377 | 27.272| | 25.138
| | | | | | 25.248|
5 | 130 | 32 | 28 | 375 | 23.225| | 25.248
| | | | | | 25.248|
6 | 130 | 32 | 28 | 377 | 27.272| |
+------+----------+---------+------------+-------+-------+-------
Means.| 130 | 32 | 28 | 2741/2 | | | 25.101
| | | | | | knots
-------------+----------+---------+------------+-------+-------+-------
--_Engineering_.
* * * * *
SOME RECENT HIGH-SPEED TWIN SCREWS.
[Footnote: A paper recently read before the Institution of Naval
Architects, London.]
By E.A. LINNINGTON.
One of the most interesting and valuable features in the development of
naval construction in recent years is the great advance which has been made
in the speeds of our war ships. This advance has been general, and not
confined to any particular vessel or class of vessel. From the first class
armored fighting ship of about 10,000 tons displacement down to the
comparatively diminutive cruiser of 1,500 tons, the very desirable quality
of a high speed has been provided.
These are all twin screw ships, and each of the twins is driven by its own
set of engines and line of shafting, so that the propelling machinery of
each ship is duplicated throughout. The speeds attained indicate a high
efficiency with the twin screws. In all ships, but more especially in high
speed ships, success depends largely upon the provision of propellers
suited for the work they have to perform, and where a high propulsive
efficiency has been secured, there is no doubt the screws are working with
a high efficiency. The principal purpose of this paper is to record the
particulars of the propellers, and the results of the trials of several of
these high speed twin screw ships. The table gives the leading particulars
of several classes of ships, the particulars of the screws, and the results
obtained on the measured mile trials from a ship of each class, except C.
The vessels whose trials are inserted in the table have not been selected
as showing the highest speeds for the several classes. Excepting C, they
are the ships which have been run on the measured mile at or near the
designed load water line. On light draught trials, speeds have been
attained from half a knot to a knot higher than those here recorded. No
ship of the class C has yet been officially tried on the measured mile, but
as several are in a forward state, perhaps the actual data from one of them
may shortly be obtained. All these measured mile trials were made under the
usual Admiralty conditions, that is to say, the ships' bottoms and the
screws were clean, and the force of the wind and state of the sea were not
such as to make the trials useless for purposes of comparison. On such
trials the i.h.p. is obtained from diagrams taken while the ship is on the
mile, and the revolutions are recorded by ruechanical counters for the time
occupied in running the mile. Not less than four runs are made during a
trial extending over several hours. The i.h.p. in the table is not
necessarily the maximum during the trial, for the average while on the mile
is sometimes a little below the average for the whole of the trial. The
revolutions are the mean for the two sets of engines, and the i.h.p. is the
sum of the powers of the two sets. The pitch of the screw is measured. The
bolt holes in the blade flanges allow an adjustment of pitch, but in each
case the blades were set as nearly as possible at the pitch at which they
were cast. The particulars given in the table may be taken to be as
reliable and accurate as such things can be obtained, and for each ship
there are corresponding data; that is, the powers, speeds, displacements,
revolutions, pitches, and other items existed at the same time. There are a
few points of detail about these propellers which deserve a passing notice.
In Fig. 1 is shown a fore and aft section through the boss. It will be
observed that the flanges of the blades are sunk into the boss, and that
the bolts are sunk into the flanges. The recess for the bolt heads is
covered with a thin plate having the curve of the flange, so that the
flanges and the boss form a section of a sphere. This method of
construction is a little more expensive than exposed flanges and bolts,
which, however, render the boss a huge churn. With the high revolutions at
which these screws work, a spherical boss is extremely desirable, but, of
course, the details need not be exactly as shown in the illustration. The
conical tail is fitted to prevent loss with eddies behind the flat end of
the boss, and is particularly valuable with the screws of high speed ships.
The light hood shown on the stern bracket is for the purpose of preventing
eddies behind the boss of the stern bracket, and to save the resistance of
the flat face of the screw boss. The edges of the blades are cast sharp,
instead of being rounded at the back, with a small radius, as in the usual
practice--the object of the sharp edge being the diminution of the edge
resistance. The driving key extends the whole length of the boss, and the
tapered shaft fits throughout its length.
[Illustration: FIG. 1.]
These points of detail have been features of all Admiralty screws for some
years.
The frictional resistance of screw propellers is always a fruitful source
of inefficiency. With a given screw, the loss due to friction may be taken
to vary approximately as the square of the speed. This is not to say that
the frictional resistance is greater in proportion to the thrust at high
than at low speeds. The blades of screws for any speed should be as smooth
and clean as possible, but for high speed screws the absolute saving of
friction may be considerable with an improvement of the surface. There is
no permanent advantage in polishing the blades. No doubt there is some
advantage for a little time, and, probably, better results may thereby be
secured on trial, but the blades soon become rough, and shell fish and weed
appear to grow as rapidly on recently polished blades as on an ordinary
surface. These screws are of gun metal. They were fitted to the ships in
the condition in which they left the foundry. It appears that within
certain limits mere shape of blade does not affect the efficiency of the
screw, but, with a given number of blades and a given disk, the possible
variations in the form or distribution of a given area are such that
different results may be realized. The shapes of the blades of these
propellers are shown in Figs. 2, 3, and 4. It will be seen the shapes are
not exactly the same for all the screws, but the differences do not call
for much remark.
[Illustration: FIG. 2., FIG. 3. & FIG. 4.]
Fig. 2 shows the blades for the A screw. C and D have the same form. Fig. 3
shows in full lines the blades of the B screw, and, though very narrow at
the tips, they, like A, are after the Griffith pattern. The blades of E and
F are of a similar shape, as shown in Fig. 4, and approach an oval form
rather than the Griffith pattern. The particulars of these propellers would
be considered incomplete without some reference to their positions with
respect to the hulls. When deciding the positions of twin screws, there is
room for variation, vertically, longitudinally, and transversely. For these
screws, the immersions inserted in the table give the vertical positions.
The immersion in A is 9 ft., showing what may be done in a deep draught
ship with a small screw. Whatever the value of deep immersion may be in
smooth water, there can be no question that it is much enhanced in a
seaway. The longitudinal positions are such that the center of the screw is
about one-fifth of the diameter forward of the aft side of the rudder post.
The positions may, perhaps, differ somewhat from this rule without
appreciably affecting the performance, but, if any alteration be made, it
would probably be better to put the screws a little farther aft rather than
forward. The forward edges of the blades are from 2 ft. to 3 ft. clear of
the legs of the bracket which carries the after bearing. The transverse
positions are decided, to some extent, by the distance between the center
lines of the engines. As regards propulsive efficiency, it would appear
that the nearer the screws are to the middle line, the less is the
resistance due to the shaft tubes and brackets, and the greater is the gain
from the wake in the screw efficiency, but, on the other hand, the greater
is the augment of the ship's resistance, due to the action of the screws.
Further, the nearer the screws are to the hull, the less are they exposed.
But experience is not wanting to show that the vibration may be troublesome
when the blades come within a few inches of the hull. The average of the
clearances between the tips of the blades and the respective hulls is about
one-eighth of the diameter of the screw.
An interesting and noteworthy fact in connection with these propellers is
the wide differences in the pitches and revolutions, though the products of
the two do not greatly vary. Such differences are extremely rare in the
mercantile marine for similar speeds, but in war ships they are inseparable
from the conditions of the engine design. As a general rule, with
(revolutions x pitch) a constant, an increase of revolutions and the
consequent decrease of pitch allow a diminution of disk and of blade
area--other modifying conditions, such as the thrust, slip, number, and
pattern of blades, being the same. The screws for E and F are interesting,
because, with practically the same speeds and slips, there is a
considerable difference in the revolutions. It will be observed that F is a
vessel of finer form and a little less displacement than E, and, therefore,
has less resistance. Although E has the greater resistance and the screw
the smaller pitch/diameter, the higher revolutions permit the use of a
smaller screw. But from this example the influence of the high revolutions
in diminishing the size of screw does not appear so great as some empirical
rules would indicate. The screws for A and B are also worthy of attention.
Although the ship A has a much greater resistance than B, the screw of the
former is much the smaller, both in the blade area and the disk. A's
screws, however, in addition to 22 per cent. more revolutions than B, have
a much larger slip, and the blades have rather a fuller form at the tips.
Compared with the practice in the mercantile marine, the revolutions of
these screws are very high, and from the foregoing remarks it may appear
that much larger screws would be required for a merchant ship than for a
war ship of the same displacement and speed. There would, however, be
several items favorable to the use of small screws. For a given
displacement the resistance would be less in the mercantile ship, and with
the lower revolutions the proportion of blade area to the disk could be
increased without impairing the efficiency. Thus in passing from the war
vessel to a merchant ship of the same displacement, there are the lower
revolutions favorable to a larger screw, but, on the other hand, the
smaller resistance, larger proportion of blade area, and the coarser pitch,
are favorable to a diminution of the screw. The ship B has a very large
screw at 88 revolutions, but the tips are very narrow. If the blade were as
dotted for a diameter of 16 ft., the same work could be done with the same
revolutions, but with a little coarser pitch and a little more slip.
There is something to be said for large screws with a small proportion of
blade area to disk. For instance, two bladed screws have frequently given
better results than four bladed screws of smaller diameter, neglecting, of
course, the question of vibrations. Twin screws, however, should, as a
rule, be made as small as possible in diameter without loss of efficiency.
The advantages of small twin screws are the shorter shaft tubes and stern
brackets, deeper immersion, and less exposure as compared with large
screws. The exposure of the screws is usually considered an objection, but,
perhaps, too much has been made of it, for those well qualified to speak on
the subject consider that careful handling of the ship would, in most
cases, prevent damage to the screws, and that where the exposure is
unusually great, effectual protection by portable protectors presents no
insuperable difficulty.
HIGH SPEED TWIN SCREWS.
---------------------------------------------------------------------
|Ship A.|Ship B.|Ship C.|Ship D.|Ship E.|Ship F.
---------------------------------------------------------------------
Length, ft. | 325 | 315 | 300 | 300 | 220 | 250
Breadth, ft. | 68 | 61 | 56 | 46 | 34 | 321/2
| | | | | |
Draught on trial, | 26 ft | 24 ft | | 15 ft | 12 ft | 13 ft
forward. | 2 in | 6 in | .... | 6 in | 10 in | 1 in
| | | | | |
Draught on trial, | 27 ft | 25 ft | | 19 ft | 15 ft | 14 ft
aft. | 3 in | 6 in | .... | 9 in | 2 in | 7 in
Displacement, | | | | | |
tons. | 9,690 | 7,645 | 5,000 | 3,584 | 1,560 | 1,544
I.M.S., sq. ft. | 1,560 | 1,287 | 1,000 | 744 | 438 | 392
Speed of ship, | | | | | |
knots. | 16.92 | 17.21 | 18.75 | 18.18 | 16.91 | 17
I.H.P. |11,610 |10,180 | 8,500 | 6,160 | 3,115 | 3,045
Revolutions per | | | | | |
minute. | 107.2 | 88 | 120 | 122.6 | 150.4 | 132.1
| | | | | |
Pitch of | 19 ft | 22 ft | 18 ft | 17 ft | 12 ft | 14 ft
screw. | 5 in | | 9 in | 6 in | 71/2in | 9 in
| | | | | |
Slip. per cent | 17.6 | 10 | ... | 14.2 | 9.7 | 11.4
| | | | | |
Diameter of | 15 ft | 18 ft | 14 ft | 13 ft | 10 ft | 11 ft
screw. | 6 in | | 6 in | | 6 in |
| | | | | |
Diameter of | 4 ft | 4 ft | 3 ft | 3 ft | 2 ft | 2 ft
boss. | 4 in | 11 in | 9 in | 5 in | 9 in | 10 in
Number of blades | 4 | 4 | 3 | 3 | 3 | 3
Blade area of one | | | | | |
screw. | 72 | 87 | 60 | 47 | 24 | 24
Shape of blade. |Fig. 2.|Fig. 3.|Fig. 2.|Fig. 2.|Fig. 4.|Fig. 4
Pitch | | | | | |
---------- | 1.25 | 1.22 | 1.3 | 1.34 | 1.2 | 1.34
Diameter | | | | | |
Disk | | | | | |
-------- | 2.62 | 2.92 | 2.75 | 2.82 | 3.6 | 3.96
Blade area | | | | | |
Immersion of | 9 ft | 5 ft | | 4 ft | 2 ft | 1 ft
screw. | | 3 in | .... | 4 in | 9 in | 10 in
--------------------------------------------------------------------
The slips of these screws vary from 10 to 171/2 per cent., which is certainly
not an extensive range, considering the widely different working
conditions. Slip, as an indication of the efficiency of the screw, is not
only an interesting subject, but it is often one of importance. In these
ships, however, there is nothing about the slips which would give rise to
any doubts as to the fitness of the screws for their work.
[Illustration: FIG. 5. & FIG. 6.]
The ancient fallacy that small slip meant a high screw efficiency was
supported by the great authority of the late Professor Rankine. Experience
proved that considerable slips and efficient screws were companions. The
late Mr. Froude offered an explanation of this general rule in a paper read
before this Institution in 1878, and gave a curve of efficiency with
varying true slip. In Mr. R E. Froude's paper last year there was a form of
this curve, with an arbitrary abscissa scale for the slip, devised to
illustrate in one diagram the wide conditions covered by his experiments.
In the screws now under consideration, the values of the pitch/diameter
vary only from 1.2 to 1.34, and for these the abscissa values for the same
slips do not differ much. Taking the mean value, and bringing the slips to
a common scale, Fig. 5 is obtained, which would approximately represent the
relation between the efficiency of any one of these screws and its true
slip, if this curve were applicable to full sized screws propelling actual
ships. The slips in Fig. 5 being real or true, are not the slips of
commerce, which are the apparent slips, such as those given in the table.
Let us endeavor to split up these real slips into the apparent slips and
another item, the speed of the wake. We then at once meet with the
difficulty that the wake in which the screw works has not a uniform motion.
Complex, however, as are the motions of the wake, the screw may be assumed
to work in a cylinder of water having such a uniform forward velocity as
will produce the same effect as the actual wake on the thrust of the screw.
It is then readily seen that the real slip is the sum of the apparent slip
and the speed of the hypothetical wake. To make this clear, let V be the
speed of the ship, Vs the speed of the screw, _i.e._, revolutions x pitch,
and V the speed of the wake; then--
Apparent slip = Vs - V.
Real slip = Vs - speed of ship with respect to the wake.
" = Vs - (V - V) = (Vs - V) + Vw.
" = Apparent slip + speed of the wake.
If the apparent slip be zero, the real slip is the speed of the wake, and
if the apparent slip be negative, the real slip is less than the speed of
the wake. The real slip is greater than the apparent slip, and can never be
a negative quantity. From Mr. Froude's model experiments, it appears that
this speed of wake for the A class of ship amounts to about 10 per cent. of
the speed of the A screw. If this value is correct, then the real slip is
(10 + 17.6) per cent., or 27.6 per cent. This is shown in Fig. 6, where O
is the point of no slip, being 17.64 from the point of real slip. Slips to
the right of O are positive apparent slips, slips to the left are negative
apparent slips. The vessel F would certainly have a wake with a speed
considerably less than that of A's wake. From the model experiments, the
wake for F is about one-half that for the A class, or, roughly, 5 per cent.
of the speed of the screw. For the ship F, O is the point of no apparent
slip, and the real slip is (5 + 11.4) or 16.4 per cent. For E, the point of
real slip is approximately the same as for F. For B and D, the positions on
the curve would be about the same. The ship B has a higher speed of wake
than D, but the screw D has the greater apparent slip. The influence of the
number of blades on the scale for the slip has been neglected. If this
efficiency curve were applicable to full sized screws propelling actual
ships, and if the determination of the wakes were beyond question, then we
should have a proof that our screws were at or near the maximum efficiency.
But, as we know, from the total propulsive efficiencies, that the screws
have high and not widely different efficiencies on these ships, we may
argue the other way, and say that there is good reason to consider that at
least the upper part of the curve agrees with experience obtained from
actual ships. Now take Fig. 6 and consider the general laws there
represented. Take the speed of the wake as 10 per cent. of the speed of the
screw, which is probably an average of widely different conditions,
including many single as well as twin screw ships. Then this curve shows
that considerable negative slips mean inefficient screws; that screws may
have very different positive slips without any appreciable difference in
their efficiencies; and that very large positive slips and inefficient
screws may be companions. For instance, a screw with a large positive slip
in smooth water is frequently inefficient at sea against a head wind, which
increases the resistance, and necessitates an increase of slip. I venture
to say that these statements, taken in a general manner, are not at
variance with experience obtained from the performances of screw ships.
Before it is possible to satisfactorily decide if this curve applies in a
general manner to full sized screws propelling ships, we require the
results of trials of various ships where the screws are working about the
region of no slip. Model experiments teach that the scale for the slip
varies with the design of the screw, and that with a given screw the speed
of the wake (which decides the point of no apparent slip) varies with the
type of ship and with the position of the screw with respect to the hull.
Remembering these disturbances, it is not improbable that it may be
possible to account for or explain what at first sight may appear
departures from the curve. The diameters of the screws in the table are not
compared with the diameters given by the method explained by Mr. Froude in
his paper last year, for there are differences in the slips, the
proportions of blade area to disk, and, to some extent, in the shapes of
the blades, which are not taken into account in that method. Assuming,
however, as Mr. Froude does, a constant proportion of blade area to disk,
and a uniform pattern of blade, the determination of the diameter for a
given set of conditions may, as a rule, be a complete solution of the
problem of the design of a screw, but these assumptions do not cover all
the necessities of actual practice, which make it extremely desirable to
know something about the influence or efficiency of various proportions of
blade area to disk, and of the form or distribution of a given area.
During the discussion which followed, Mr. John said that, both as regarded
the mercantile marine and the Royal Navy, there were few data to work upon,
but few ships having been built with twin screws. Mr. Linnington's
proportions of pitch to diameter of 1.2 to 1.34 was not invariably adhered
to. He mentioned a couple of small twin screw vessels where the proportion
of pitch to diameter came nearly to 1.5, and he remembered a few years ago
the propellers in one of these vessels being changed and the pitch
increased, the result being a very considerable improvement. He believed
they might go with quick running twin screw engines to a larger proportion
of pitch to diameter than they could with a single screw. He might instance
the change in the Iris. She was first engined with the pitch equal to the
diameter, and she gained two knots or thereabout when the diameter was
reduced 2 ft. and the pitch increased 2 ft.
Admiral De Horsey said that he tried experiments with the single screw in
the Aurora. She had a feathering serew, and when the sails were used to
assist, they commonly altered the pitch of the screw according to the
strength of the wind. The screw could be altered while it was revolving,
and as the wind freshened they coarsened the pitch, and when they wanted to
stop the engines they coarsened the pitch so as to bring the screw right
fore and aft, so that they never altered the way of the ship in changing
from steam to sail alone. The reason why twin screws had been adopted in
the navy was that if one was damaged there was the other still available.
But it gave them a still further advantage, as it enabled them to have a
fore and aft bulkhead, which with a single screw was difficult. The
mercantile marine had not as yet looked favorably on twin screws. Their
finest and fastest ships were single screws, probably because, in very bad
weather, the single screw was better.
Mr. Spyer said that in designing propellers for ships of war, they were
obliged to attempt to obtain the highest possible speed, and that was not
necessarily coincident with a propeller of maximum efficiency. On the other
hand, for mercantile purposes, coal consumption was obviously of paramount
importance, and the speed of any particular vessel must be obtained with
the smallest possible amount of indicated horse power, and a propeller of
maximum efficiency. Regarding the position of the propellers in a small
pinnace, the propellers were shifted six or seven inches further out, and
with about ten per cent. less indicated horse power she obtained three
tenths of a knot more speed.
Mr. Barnaby asked Mr. Linnington whether, in designing twin screws for a
vessel of 8,000 i.h.p., he would make each screw, which would have to take
4,000 i.h.p., of the same diameter as a screw for a single ship of 4,000
i.h.p., of the same speed. Unfortunately in high speed vessels, from one
point of view, the faster they went for a given power the smaller the
diameter of the screw had to be, and the larger the pitch, so that in very
high speed twin screw vessels the ratio of pitch to diameter would be found
to come out very great indeed. In a twin screw torpedo boat, to be tried
shortly, they had a ratio as high as 1.64. In the case of the Inflexible it
was found, owing possibly to the position of the screw, that the whole of
the plates immediately over the screws were damaged. Mr. Beckett Hill had
been using, during the past three or four years, the twin screw steamers
the Ludgate Hill, Richmond Hill, and Tower Hill. These were all over 4,000
tons register, and indicated, when at work at full speed, 2,500 h.p. Before
he and his friends built these steamers, they built some very large tug
boats on the twin screw principle. At the present moment, four of the
fastest steamers building for the Atlantic service were to have twin
screws. The great obstacle to the extension of the twin screw in the
mercantile navy had been the fear that the projection of these screws would
make the vessels very difficult to handle, but he had found no such
difficulties. He had found it an advantage to put the point of the
propeller as near the deadwood as he could, without actually touching it,
and in the large steamers, as well as in the tugs, the distance was a few
inches. As to the point of safety, he thought it a great advantage to have
twin screws, and on two occasions twin screw vessels had met with accidents
which, but for the twin screws, would have necessitated their putting back
to New York for repairs. The Richmond Hill, on one occasion, met with an
accident to her machinery two days after leaving New York; but she was able
to come on with the second set of engines, and was only one day late in the
passage. No difficulty had been found in the docking and undocking of these
vessels, either in London or Liverpool, and while with single screw vessels
they had sometimes to employ one or two dock boats to dock and undock them,
they never had to do so with the twin screw vessels. These vessels were 400
ft. long, with 48 ft. breadth of beam--a very large size to handle in a
river like the Thames. He noticed in the paper a propeller with a diameter
of 15 ft. 6 in. to indicate 11,110 h.p., so that a great Atlantic steamer,
which should indicate 11,000 or 12,000 h.p., and have a beam of about
65ft., would have her screws very well protected.
Mr. White said that as soon as it was found that with twin screws they lost
nothing in efficiency, ship owners generally were contemplating their
adoption, an admirable example of which had been set in the vessels of the
Hill line. In adopting twin screws, the question whether they should
overlap was one that deserved very serious consideration, and it was
interesting to know, from experience gained by the vessels of the Hill
line, that there was no difficulty in the way of the projection of the
screws. With a moderate power, and with vessels of considerable size, the
screws were well sheltered: but in the large ships which were contemplated,
where there must necessarily be larger screws, this might be different, and
become a difficulty.
Mr. Linnington, in reply, said there was no reason to think that the twin
screw at sea might not be as satisfactory, in comparison with the single
screw, as it appeared in smooth water. As a matter of fact, one of the
great advantages of twin screws was that at sea the condition of weather
which would bring the single screw out of the water, and make it extremely
inefficient, would have no appreciable effect on the twin screws. In
vessels of deep draught especially, they were well immersed, and they were
really more efficient at sea than in smooth water. In ships of full form,
the longitudinal position of the screws was of importance; but in the ships
referred to in this table the run was very fine, and the screws were well
covered by the hull. He did not think, in such a case, any small difference
in longitudinal position would affect the performance. If any alteration
were made, it would probably be better to put the screws farther off. When
the rudder was hard over, the blades of the screw should be about a foot
clear of the rudder.--_Industries_.
* * * * *
RECENT ADVANCES IN SEWING MACHINERY.
[Footnote: A recent lecture before the Society of Arts, London.]
By JOHN W. URQUHART.
The distinct improvements in sewing machinery to which I would invite your
attention this evening have reference more particularly to the results of
inventive effort within the past ten years. But although marked development
in the machines has occurred in so short a time, it may be taken for
granted that those advances are but the accumulated results of many years'
prior invention and experience of stitching appliances.
The history of the sewing machine, and the decision of the great question,
Who invented an apparatus that would unite fabrics by stitches? do not at
present concern us. Many sources of information are open to those who would
decide that extremely involved problem. But whether the production of the
first device of this kind be claimed for England or for America, it is
quite certain that no one man invented the perfect machine, and that those
fine specimens of sewing apparatus shown here to-night embody the labors of
many earnest workers, both in Europe and America.
Most of us are familiar with the arrangements of an ordinary lock stitch
machine, and an able paper by Mr. Edwin P. Alexander, embracing not only a
good account of its history, but most of the elements of the earlier
machines, has already (April 5, 1863), been read before you. This, and
sundry descriptions of such apparatus in the engineering papers, confine my
remarks to the more recent improvements in three great classes of machines.
These are, briefly, plain sewing machines; sewing machines as used in
factories, where they are moved by steam power; and special sewing
machines, embracing many interesting forms, only recently introduced. We
have thus to consider, in the first place, the general efficiency of the
machine as a plain stitcher. Secondly, its adaptability to high rates of
speed, and the provision that has been made to withstand such velocities
for a reasonable time. And, thirdly, the apparatus and means employed to
effect the controlling of the motive power when applied to the machines.
To deal with the subject in this way must, I fear, involve a good deal of
technical description; and I hope to be pardoned if in attempting to
elucidate the more important devices, use must be made of words but seldom
heard outside of a machinists' workshop.
It appears scarcely necessary to premise that the sewing machine of twenty
years ago has almost faded away, save, perhaps, in general exterior
appearance; that the bell crank arms, the heart cams, the weaver's
shuttles, the spring "take ups," rectangular needle bars, and gear wheels,
have developed into very different devices for performing the various
functions of those several parts.
The shuttle is perhaps the most important part of a lock stitch machine.
But what is a shuttle? So many devices for performing the functions of the
early weaver's shuttle have been introduced of late, that the word shuttle,
if it be used at all, must not be accepted as meaning "to shoot." We have
vibrating shuttles, which are, strictly speaking, the only surviving
representatives of the weaver's shuttle in these new orders of machines;
and stationary shuttles, oscillating shuttles, and revolving shuttles,
besides the earlier rotating hook, in several new forms, difficult to name.
But the general acceptation of the word shuttle, as indicating those
devices that pass bodily through the loop of upper thread, is, I venture to
think, sufficiently correct.
Many changes have been effected in the form, size, and movements of the
shuttle, and we may profitably inquire into the causes that have induced
manufacturers to abandon the earlier forms. The long, weaver's kind of
shuttle, originally used by Howe and Singer, had many drawbacks. Mr. A.B.
Wilson's ingenious device, the lock stitch rotating hook, was not free from
corresponding faults. The removal of these in both has led to the adoption
of an entirely new class of both shuttles and revolving hooks. It is well
known that the lock stitch is formed by the crossing of two threads, one of
which lies over, and the other under, the cloth to be sewn. This crossing
point, to insure integrity of the stitch, must occur as nearly as possible
in the middle of the thickness of the fabric. The crossing must also be
effected while a certain strain, called tension, is imposed upon both
threads. If the tension of one thread should outweigh that of the other,
the locking point becomes displaced. If the tension be insignificant, the
stitches will be loose. If the tension should vary, as in the long shuttle,
there will occur faulty points in the seam.
In the earlier rotating hook the tension depended upon the friction
developed between the spool and the hook. This tension, therefore, varied
in proportion to the speed of the latter, and could never be constant. This
was quite apart from the frictional resistance offered to the upper thread
in passing over the cavity of the hook.
In the shuttle the tension was obtained by threading through holes in the
shell, or beneath a tension plate, as in Howe's machine. This tension, so
long as the reel ran between spring centers, was never constant. The
variation was chiefly due to the angular strain set up when unwinding from
the reel. This strain varied according to the point of unwinding. It was
light in the middle of the reel and heavy at either extremity. These
drawbacks caused immense anxiety to the first makers of sewing machines,
and numerous attempts to overcome them led to little improvement. With
reference to high rates of speed, the older shuttle, requiring a long and
noisy reciprocation, had its disadvantages.
The only effective remedy for these drawbacks was a radical one. It was
necessary to substitute depth of reel for length. Hence, several attempts
have been made to construct disk or ring shuttles. Many forms of those have
been tried. They all depend upon the principle of coiling up the thread in
a vertical plane, rather than in horizontal spirals. Some makers placed the
disk in a horizontal plane, and caused it to revolve. Nothing could be
worse, as will be seen, if we follow the course the enveloping loop must
take in encircling such a shuttle. But a complete solution of the
difficulty of employing a ring shuttle has been achieved in the oscillating
form, invented by Mr. Phil. Diehl, and known as Singer's (Fig. 1). A short
examination of it may profitably engage your attention. The shuttle itself
is sufficiently well known, but certain features of it, and to which it
owes its efficiency, appear to call for some explanation. Its introduction
dates back some years, during which time it has undergone certain
modifications.
[Illustration: FIG. 1.]
It consists of a thick disk bobbin of thread, _h_, fitting loosely in a
case constructed in the form of a bivalve, _a_ and _d_. This case is
furnished with a long beak, usually forming a continuation of the
periphery. The beak is intended to enter and detain the loops of upper
thread, and lead them so that they ultimately envelop the shuttle, a motion
of the thread which is chiefly due to the oscillation of the shuttle in a
vertical plane. The oscillating movement is to the extent of 180 degs. of
the circle, which suffices to cast the loops freely over the shuttle. The
center of oscillation is not coincident with the center of the shuttle; but
it is nearly so with the periphery of the thread reel, and exactly
coincides with the point where the under thread is drawn from the shuttle,
_g_. The shuttle thread is thus entirely freed from any tendency to twist,
an objection frequently urged against circular or revolving shuttles. It
will be observed, also, that the body of the shuttle is extremely narrow.
Bulging of the thread loops to one side or the other is thus obviated.
But the long beak in this description of shuttle serves an important
purpose other than that of seizing the upper thread loops, otherwise a very
short beak would be preferable. It adds so much to the efficiency of the
machine that a little further explanation of it appears essential. In the
old fashioned machines the thread required to envelop the shuttle was
dragged downward through the cloth, while the needle still remained in the
fabric. This necessitated the use of large needles with deep side channels,
to enable the thread to run freely, and as a consequence the punctures that
had to be made in the fabric were unnecessarily large, and could not in any
case be entirely filled by the thread, a condition which is now recognized
as essential in linen stitching and for waterproof boots.
The long beak in both shuttles and hooks offers an immediate solution of
the old difficulty experienced with long shuttles. When the needle begins
to rise, the shuttle commences to oscillate, through the loop, the motions
so coinciding that the long beak, c, merely detains the loop until the eye
of the needle has ascended above the cloth; then, and then only, does the
envelopment of the shuttle commence, and the thread required for it flows
downward through the puncture. The envelopment is completed before the
needle has attained its highest point, and the consequent loose thread is
immediately pulled up by a lever, called a positive take-up, before the
needle begins to descend for a fresh stitch. In this way little or no
movement of the thread is required in the cloth while the puncture made is
occupied by the needle. The result is the capability of such apparatus to
work with an incredibly fine needle--indeed, so fine as to be no thicker
than the incompressed thread itself. This would have been considered quite
impossible of accomplishment by our earlier machine makers. The advantage
thereby gained in stitching linen goods, and in sewing leather, where every
puncture of the needle should be quite filled by the thread, is at once
apparent. Indeed, a rubber or leather sack, stitched in this way, will
contain water without leakage--a very extreme test.
_Revolving Shuttles_.--The class of shuttles known as revolving or
rotating, and which really consist of a combination of the disk shuttle and
the earlier rotating hook of Wilson, have been under trial by several
makers for many years. If, for example, the oscillating shuttle we have
just examined were to complete its circular movement, it would constitute a
revolving shuttle, but would not be quite similar to those devices now
known as such. The most remarkable device of this kind yet introduced is to
be found in Wheeler & Wilson's machine known as No. 10 D, and invented by
Mr. Dials last year. It consists, in fact, of a detached hook, and its
inventor declines to class it with shuttles at all, styling it a detached
hook. It consists of an exterior shell or skeleton of steel, capable of
rotation in an annular raceway. Its detachment from the axis forms a
striking exception to the general construction of interlocking apparatus in
this company's machines. Under the beak of this curious device is found an
oblong recess, into which fits loosely a carrier or driver, rotating with a
differential or variable motion. The space between the carrier and the
sides of the recess is sufficient to permit the free passage of the thread
in encircling the shuttle, and the differential movement ingeniously
releases the contact between the hook and carrier. The skeleton of this
device is only one-sided, and does not really carry its bobbin in the
course of its revolution. The bobbin is placed in a cup-like holder, which
lies within the shuttle or hook body, and is retained in position by a
latch hinged to the bed of the machine. The cup and bobbin are prevented
from partaking of the rotatory movement by a steel spur projecting from the
cup, and fitting loosely into a notch in the latch. Tension upon the under
thread is obtained by passing it under a tension plate upon the bobbin cup.
Twisting of the thread is by these means entirely obviated. In this
apparatus, the disk-like appearance of the bobbin is partially lost in its
considerable breadth, and there is thus a distinct departure from the lines
of the ring shuttles before mentioned. The diagrams exhibit the hook in
several positions during its revolution, and the position of the threads
corresponding thereto.
[Illustration: FIG. 2]
_Fixed Rotating Hooks_.--Wilson's rotating hook for lock stitch machines,
and Gribbs' hook for single thread machines, are both well known. In the
year 1872, the Wheeler & Wilson company introduced a new hook, forming an
improvement upon Wilson's original device (Fig. 3). Its chief peculiarity
consists in the extension of the termination of the periphery, forming a
long tail piece, quite overlapping the point, and serving as a guard, both
to keep off the bobbin thread and to prevent collision between bobbin and
needle.
[Illustration: FIG. 3.]
This improved class of hooks are provided with a much deeper cavity than
those first introduced, an arrangement permitting of the employment of a
more commodious bobbin, which is generally covered by a cap, as in the
revolving shuttle, but free to revolve. In some cases the cap carries a
tension plate preventing its revolution with the hook. But beyond these
improvements on Wilson's original device, the utility of the hook mainly
depends upon two things quite apart from the hook itself. These are the
dispensing with the old fashioned check brush and the use of a positive
take-up.
Thus, in the original machine, the stitch was pulled up by the succeeding
revolution of the hook. For while one revolution sufficed to cast it over
the spool, a second turn was requisite to complete the stitch. In this way,
to make a first stitch with such an apparatus required two turns of the
rotating hook. The improvements mentioned enable the machine to complete a
stitch with one turn of the hook--an important step in advance, when we
consider that by the old method each length of slack thread must be
tightened up solely through the fabric and the needle eye. But this
particular arrangement bears so much upon the introduction of the positive
take-up itself that further reference to it must be reserved until that
device has been described.
_Simple Thread Hooks_.--The best known of these is Willcox & Gibbs. It has
been so often described, that no further reference to it may be made. It
continues to make the same excellent twisted stitch as it produced
twenty-five years ago.
_Of Vibrating Shuttles_.--These are shuttles of the long description,
moving in a segment of a circle. There are several varieties. The most
novel machine of this kind is the vibrating shuttle machine just produced
by the Singer Manufacturing Company. In this case the shuttle itself
consists of a steel tube, into the open end of which the wound reel is
dropped, and is free to revolve quite loosely. Variation of tension is thus
obviated in a very simple manner. The chief point of interest in the
machine is undoubtedly the means employed in transferring the motion from
the main shaft to the underneath parts, an arrangement as ingenious and
effective as any device ever introduced into stitching mechanism. It is the
invention of Mr. Robert Whitehall, and consists of a vertical rocking shaft
situated in the arm of the machine Motion is imparted to it by means of an
elbow formed upon the main shaft acting upon two arms, called wipers,
projecting from the rocking shaft, the angle formed by the arms exactly
coinciding with that of the elbow in its revolution. This admirable motion
will no doubt attract much attention from mechanists and engineers.
_The Lock Stitch from Two Reels_.--In the early days of the sewing machine,
the makers of it often met with the question, "Why do you use a shuttle at
all? Can you not invent a method of working from a reel direct?" The
questioner generally means a reel placed upon a pin, just as the upper reel
is placed. The reply to such a query is, of course, that to produce the
lock stitch in that way is impossible--as indeed it is.
But many ingenious machinists have pondered long over the problem, and
several clever contrivances have been invented with a view to its solution.
It may scarcely be necessary to say that the best manufacturers of sewing
machines have conducted experiments with the same object in view, and the
result has always been a return to the shuttle, with its steel bobbins.
Why is this, and how is it that a very big shuttle cannot be used, large
enough, indeed, to accommodate any bobbin within itself? The answer is very
simple. It has been done over and over again.
Since the whole bulk of the under thread must pass through the loop of the
upper one, it, is quite clear that the size of that loop must be
proportioned to the bulk of the shuttle. Thus, a small shuttle would,
perhaps, be covered by an inch of thread, while our supposed mammoth
shuttle might require ten times that amount. Now, let us consider that to
sew an inch of thread into lock stitches frequently involves its being
drawn up and down through both needle and fabric twenty times. This means
considerable chafing, and possible injury to the thread.
But if we were to sanction the use of capacious shuttles, ten inches of
thread must undergo this chafing and seesaw treatment, and under the above
conditions every part of the ten inches must pass up and down two hundred
times--treatment that might reasonably be expected to leave little "life"
in the thread. But in spite of this tremendous drawback, there are machines
offered for sale made with such shuttles.
For reasons that I have now pointed out, it is quite clear that a large
shuttle or bobbin is by no means an unmixed advantage. Indeed, the very
best makers of sewing machines have always striven to keep down the bulk of
the shuttle, and in those splendid machines shown here to-night the use of
the small shuttles is conspicuous. It may be contended that small bobbins
frequently require refilling, which is quite true, but the saving of the
thread effected thereby, not to mention that of the machine itself, amply
compensates for the use of small shuttles. Apart from this, however, it is
no longer necessary to wind bobbins at all. Dewhurst & Sons, of Skipton,
and Clark & Co., of Paisley, have produced ready wound "cops" or bobbins of
thread for placing direct into shuttles. Thus no winding of bobbins is
necessary, and indeed the bobbins themselves are dispensed with. I believe
that the slightly increased cost of the thread thus wound is the only
present bar to the extensive introduction of ready wound "cops."
_Of Thread Controllers_.--One of the earliest difficulties encountered by
the maker of a sewing machine was that of effectually controlling the loose
thread after it had been cast off the shuttle. In some machines this slack
thread amounts to six, in others to one or two inches. Howe got over the
difficulty by passing his thread, on its way to the needle, over the upper
extremity of the needle bar--the ascent of the bar, then, sufficed to pull
up the slack. Singer improved upon this by furnishing his machine with a
spring take-up lever, partially controlled by the needle bar.
[Illustration: FIG. 4.]
Wilson, in the Wheeler-Wilson machine, had neither of those arrangements,
but depended upon the succeeding revolution of the hook to draw up the
slack of the preceding stitch. These devices were all far from perfect in
their operation, chiefly because they commenced to act too soon. In each
case the pulling up commenced with the rise of the needle, and the
tightening operation subjected the thread to all the friction of rubbing
its way through both needle eye and fabric. Now, an ideal take-up should
not commence to act until the needle has ascended above the fabric, and one
of the most important steps toward perfection in sewing machines was
undoubtedly attained when such a device was actually invented. In effecting
this, the means employed consists of a differential or variable cam,
rotating with the main shaft. This controls the movements of a lever called
the take-up, pivoted to the machine (Fig. 4). Not only has it been
possible by these means to control the tightening of the stitch, but the
paying out of the thread for enveloping the shuttle also, and both the
paying out and pulling up are actually effected after the needle has
ascended above the cloth. The introduction of the positive take-up, the
first forms of which appeared in 1872, not only simplifies the movements of
the shuttle or hook, but for the first time renders the making of the lock
stitch possible, while the needle has a direct up and down motion. Thus, we
find that in most of the swiftest sewing machines, the needle bar is
actuated by a simple crank pin or eccentric, there being no loop dip or
pause in its motion.
The diagram shows a positive take-up in three positions--at the
commencement of the needle's descent, during the detention of the loop by
the beak, and during the casting off of the loop. The dotted lines indicate
the path of the cam to produce these positions. The intermittent movements
of the take-up have thus led to the abandonment of variable motions in both
needle and shuttle, and particularly so in oscillating shuttle machines.
_Wheeler & Wilson's Variable Motion_.--But while the simple and direct
movement is now preferred for shuttles, both oscillating and rotary, the
revolving hooks of Wheeler & Wilson are provided with a differential
motion, and the way it is effected appears sufficiently interesting to call
for a short description. When the rotating hook has seized the loop of
thread, it makes half a revolution with great rapidity; its speed then
slackens, and becomes very slow for the remaining half a revolution. In the
first machines introduced, this was effected by means of a revolving disk,
having slots in which worked pins attached to the main shaft and hook shaft
respectively.
[Illustration: FIG. 5.]
In the later and more improved machines, the variable device is much
simplified (Fig. 5). The main shaft, leading to the rotating hook, is
separated into two portions, the axis of one portion being placed above
that of the other. A crank pin is attached to each, and these pins are
connected together by a simple link. An examination of the device itself
shows that, while the motion of the main shaft portion is uniform, that of
the hook shaft is alternately accelerated and retarded.
The picture on the screen gives a general view of the No. 10 D machine, in
which these motions are embodied, and showing the position of the positive
take-up affected by those motions, a position which is preferred for very
high speeds in this machine, especially for threads possessing little
elasticity.
_Motions of the Feeder_.--The speed attained by the fastest sewing machines
is due more to the reduction and simplification of the movements than to
any other improvement. Heavy concessions and reactions have been replaced
by direct motions, and cams have been excluded as much as possible. Mr.
A.B. Wilson's famous invention of the four motion feeder depended upon both
gravity and a reacting spring for two motions. Singer improved upon it by
making three of the motions positive, a spring being used for the drop. But
a really positive four motion feeder was long sought by inventors.
Hitherto the reaction of the feeder--that is, its descent and
recession--was generally attained by means of a spring. The drop and ascent
are now effected by means of a separate eccentric in Singer's machine.
Uncertainty of action in the feed, once a cause of much inconvenience, may
now be said to be overcome. A peculiarity of the four motion feeder in
Wheeler & Wilson's machine is an arrangement enabling the operator to feed
in either direction at will.
Not less worthy of note are improvements that have been made in wheel
feeders. The wheel feed was originally much used for cloth sewing machines,
especially in Singer's system. But in recent years the drop or four motion
feeder has entirely superseded it for such purposes. The wheel feed still
holds its own, however, for sewing leather, especially in the "closing" of
boot uppers, in this country. Singer's original wheel feeder was actuated
by a friction shoe riding upon the flange of the wheel. The friction grip,
however, had certain faults, owing to the tendency of the shoe to slip when
the surfaces became covered with oil.
[Illustration: FIG. 6.]
A later form of Howe's machine used a pair of angular clutches, embracing
the flange of the wheel. In both Singer's and Wheeler & Wilson's latest
styles of machines this arrangement is simplified and improved by the use
of a single angle clutch, which is found to work even when the surfaces are
freely oiled (Fig. 6).
Any motion of the free extremity of the lever upon which the biting clutch
is formed binds the latter upon the flange of the wheel, which then
advances so long as the lever continues to move in that direction. When the
stitch is completed, the clutch is allowed to recede, and is pulled back by
a reacting spring. The bite of the clutch is given by the two opposite
corners.
The feed wheel itself is free to revolve in a forward direction, but is
prevented from rocking backward in Singer's machine by an ingenious little
device, recently introduced. It consists of a small steel roller, situated
within the angle formed by an inclined plane and the flange of the wheel,
and constantly pulled into the angle by a spiral spring. Any backward
tendency of the wheel binds the roller more firmly in the angle and stops
the wheel. Former feed wheels were checked by a brake spring or block,
which retarded the motion of the whole machine when heavily adjusted.
_Feeders for Button Hole Sewing Machines_ are almost invariably of the
wheel type, but in this case the cloth is usually carried by a clamping
device, and moved in a pear-shaped path by means of a cam cut in the feed
wheel, as shown in the samples of this wonderful kind of mechanism
exhibited here to-night.
_The Compensating System of Construction_.--Compensation for wear is a part
of the mechanist's art that appears just as essential to him as
compensation for variation of temperature is to a maker of chronometers. In
the construction of sewing machines to be run in factories by power at
their utmost speed, such a system is of the greatest importance. An
effective _system_ of compensation has been eagerly sought by the best
machine makers ever since the introduction of fast speed sewing.
Compensation has been attempted here and there in the machines for many
years, but no sewing apparatus could be said to be so compensated until the
cone compensator came into use, a device which has been taken advantage of
by various makers. Save in the shuttle race itself there is not a part of
the oscillating shuttle machine subject to serious wear that cannot be
instantly adjusted to full motion by the turning of a screw, while wear in
the shuttle race can be compensated for in the usual way. This effective
system depends upon the union of two mathematical forms, long used in
mechanism--the _cone_ and the _screw_. In screw cones we possess a perfect
compensator, and it is surprising that parts of mechanism so hung appear
subject to very little wear. Another advantage, too, is gained by the
introduction of screw cone bearings; the friction is always greatly reduced
by their use. In every case the fine adjustment of the cones is securely
maintained by locknuts (Fig. 7).
[Illustration: FIG. 7.]
But the screw cone system is not the only compensator used in sewing
machinery; where it cannot be easily introduced, other devices have been
employed.
The well known tapering needle bars of former years have been superseded by
cylindrical needle bars. The Wheeler & Wilson Company appear to be the
first who utilized the engineer's shifting box as an antifriction device
for round needle bars. They packed their bars round with felt rings, and
compressed the whole by a screw cap.
In the Singer machines the same excellent device has been adopted, hemp
packing and screw bushes being used (Fig. 8); _f_ and _g_ show the direct
action on the needle bar. This method of forming needle bar bearings,
partially of metal and partially of felt or hemp, has afforded the most
surprising results.
[Illustration: FIG. 8.]
When the bars are of hard or finely polished steel, no perceptible wear can
be detected in them, even after they have been in daily use in factories
for twelve months, whereas bars not so bushed might show considerable wear
in that space of time. The packing, to be effective, should be sufficiently
close to prevent as much as possible friction of the steel with the cast
iron needle bar ways. Lubrication of the steel is insured by keeping the
hemp packing moistened with oil.
Cylindrical needle bars, when combined with an effective system of
brushing, have proved themselves superior to every other form of slide for
lock stitch machines. But their introduction is by no means a thing of
yesterday. They were used freely in sewing machines as far back as 1860,
but were never very successful until united with the lubricating brush.
Some makers go a step further, and elaborate the system by the introduction
of steel brushes, easily renewable.
Every effort is now made to reduce, as much as possible, not only the
extent of movement of the parts in high speed machines, but the weight of
the parts themselves. Indeed, so far has this been carried that, in some of
the Wheeler & Wilson machines now shown, the needle bars consist really of
steel tubes. Small moving parts are made as light as possible, but rigidity
is secured by the free use of strengthening ribs. Many of the parts are of
cast iron, rendered malleable by annealing, and finally casehardened. Such
parts are found to be quite as durable as if made of forged steel, and are,
of course, less costly. As to the automatic tools now used in the
construction of the machines, it may be said that scarcely a file, hammer,
or chisel touches the frame or parts while they are being assembled to work
together. The interchangeable system of construction is, of course, the
only one possible for the accurate production of the millions of sewing
machines now manufactured annually.
_High Arm Construction_.--Sewing machines, as now constructed, exhibit a
rather short and very high arm, a form of framework that has been found to
contribute in no small degree to the light running capabilities of fast
speed machines. While it reduces the length of the various parts concerned
in the transference of the motive power, it adds to their rigidity and
diminishes their weight, maintaining at the same time the capacity of the
machine to accommodate the largest garments beneath the arm.
But the specific improvements in plain sewing machines, to which I have had
the honor of drawing your attention, do not exhaust the list, and, time
permitting, it might be considerably augmented. Nor must it be inferred
that advancement has taken place exclusively in those systems of sewing
machinery now before us.
_Accessories to Sewing Machines_.--The number of special attachments that
have been successfully adapted to plain sewing machines has multiplied so
rapidly of late, that only one or two of the more notable can be spoken of
on this occasion. Perhaps the most generally useful of these is the
trimmer, an arrangement consisting of a vibrating knife, which trims off
the superfluous edge of a seam as the machine stitches it. These are in
extensive use in the factories at Leicester, Nottingham, and elsewhere,
while Northampton and Norwich use the same device for paring the seams in
boot upper manufacture. The chisel-like knife is usually actuated by a cam
rotating with the main shaft, and one or two of the usual forms of this
attachment are to be seen here this evening on both lock and loop stitch
machines.
When machines are moved by the foot, there are many objections to running
the whole machine while winding the shuttle reels. We have, therefore,
several useful devices for releasing the balance wheel of the machine from
the main shaft, while winding. These are to be found both on Wheeler &
Wilson's manufacturing machine and upon Singer's highly finished "Family"
machine, which also carries a most ingenious automatic reel winder, capable
of doing all the work itself, and ceasing to act as soon as the bobbin is
filled.
The setting of the needle in a sewing machine was once quite a task.
Ofttimes it had to be adjusted by chance, in other instances by certain
guiding marks upon the needle bar. It is gratifying to know that all this
has been done away with, and that the needle has only to be inserted into
the bar, and fastened by turning a small screw. These are styled
self-setting needles, and are usually so arranged that they cannot be
adjusted wrongly as to the position of the eye.
In the Willcox & Gibbs machine, and in Singer's single thread machine,
shown here, we have an intermittent tension arrangement, which clamps the
thread at the right moment, and differs from ordinary tension devices,
inasmuch as it may be said to be automatic. The feeder, too, on these
machines is of excellent design, while the arrangements that have been
introduced into the Willcox & Gibbs straw hat sewing machine are
surprisingly effective in spinning up a hat from a loose roll of braid.
Speaking of straw hat machines, mention should be made of Wiseman's hand
stitch apparatus, as improved by Messrs. Willcox & Gibbs, and shown here
this evening. This machine employs two needles, and makes a stitch
resembling hand work at intervals, producing a short stitch at the center
of the hat, and automatically widening the space between the stitches as
the distance from the center increases. The machine itself is of wonderful
ingenuity, and must be examined to be understood.
The stitch making itself is, I believe, quite new, and is also of much
interest. A pair of needles, the width of a stitch apart, rise from beneath
through the material. One of these is an ordinary machine needle, threaded;
the other is a barbed needle. After rising above the surface, the loop of
the threaded needle is seized by a "threader," and thrown into the barb of
the barbed needle. The needles then descend, and the feed occurs, being the
length between stitches. Upon the ascent of the needles again against the
material, the loop is both given off the barb and is entered by the
threaded needle, completing the stitch.
_Of Button Hole Machines_.--The mechanism of button hole machines is so
intricate, that I can only attempt on this occasion to partially elucidate
the construction of one of them, recently introduced, namely, Singer's,
which automatically cuts, guides, and stitches the work.
[Illustration: FIG. 9.]
Fig. 9 exhibits the stitching made by this machine upon the edge of the
button hole. Fig. 10 represents the right and left hand loopers and loop
spreaders, and for the stitch making. They rock from right to left with an
intermittent motion obtained from a cam. The left hand looper carries the
under thread and interweaves it with the upper, forming the stitch,
originally invented, I believe, by Mr. George Fisher, of Nottingham, and
reinvented for the button holing machine by D.W.G. Humphreys, of
Massachusetts, U.S.A., in 1862. The loop spreaders are moved by a roller
carried upon the looper frame. Fig. 11 exhibits the feeding arrangement,
both sides of the feed wheel, the driving lever, and the shape of the path
given to the carrying clamp by the heart cam cut in the upper surface of
the feed wheel. The picture on the screen represents the upper portions of
the machine, exhibiting the conveying clamp, the to and fro dipping motions
of the needle bar, and the parts conveying motion to the arrangements
beneath the bed plate. These are shown in Fig. 12, and represent the feed
and looper cams, the feeding and looper levers, and the stitch forming
mechanism already shown. A most ingenious device in this machine is the
arrangement for automatically lengthening the throw of the feed while
stitching around the eye of the button hole. It is effected by means of a
cam, which imparts more or less leverage to the feed arm by the
intervention of a "shipper" lever, hinged to the feed lever itself. The
space of time at my disposal obliges me to recommend a personal examination
of the machine itself, to fully understand its various motions and its
action in working a button hole.
[Illustration: FIG. 10.]
[Illustration: FIG. 11.]
[Illustration: FIG. 12.]
Mention may be made of Singer's special button hole machine for making the
straight holes used in linen work, and in which a shuttle is employed. Of
Wheeler & Wilson's ingenious button hole machine for the same purpose, I am
enabled to show a diagram, in which it will be observed that the feeding
arrangements are placed above the bed plate, and are no doubt thereby
rendered easily accessible.
_Application of Power to Sewing Machines_.--There was a time when a cry
arose to the effect that the introduction of mechanical sewing would lead
to divers calamities, physical and mental. The ladies were to become
crooked in the spine, and regular operators were to become regular
cripples. It is scarcely necessary to ask, Has this been so? The operators
of to-day are, I think, superior in physical attainments to their sisters
of the needle and thread fifty years ago.
Within the past few years a revolution has taken place in the moving of
sewing machines. Domestic machines will probably always be driven by foot
power, spring, electric, and water motors notwithstanding. But the age of
treadles in the great manufacturing trades is a thing of the past. It was
not necessary for Parliament to step in and protect the workers, as was
frequently suggested by alarmists. The commercial interests of
manufacturers themselves were at stake. Machines driven by power could do
25 per cent. more work than those moved by foot. The operators, relieved of
the treadling, maintained a much better working condition; and altogether
the introduction of power driving, once well tested, became a necessity.
Power sewing machinery was speedily devised and introduced by several of
the first manufacturers, controllers of the speed of the machines followed,
and two or three splendid systems of stitching by steam power were soon
widely known.
By the kindness of three of the best manufacturers of power sewing
machinery, I am enabled to show to you, this evening, the best known
systems, arranged just as they are fitted in many large factories, as also
a sketch of the arrangements of Wheeler & Wilson's system. We have in the
first place a light shafting carrying a band wheel opposite to each
machine. By the use of a powerful electromotor, the shafting is caused to
rotate at the rate of 400 revolutions per minute by electricity. The
current is generated by the Society's dynamo machine, and is conveyed here
by copper cable. I do not know of any instance of sewing machinery in a
factory being driven by an electromotor, but such means of conveying motive
power appears admirably adapted for that purpose, when the stitching room
happens to be far removed from the main shafting or engine. But with regard
to motors for sewing machines, when special power has to be fitted down for
that purpose, my own experience leads me to speak in favor of the admirably
governed "Otto" gas engines made by Crossley Bros. These are especially
steady, a feature of no small moment in moving stitching machinery of
various kinds.
Much attention has been devoted to the invention of controllers of the
motive power supplied to sewing machines. The principle of the friction
disk has found most favor. In many cases two of these plates, fast and
loose, are placed upon the main shaft, and their separation and contact
controlled by the treadle. The great sensitiveness of the friction
attachment employed by the Singer company is due chiefly to the
transference of the friction plates to the axis of the machine itself (Fig.
13). Their contact and separation are controlled by a lever worked by a
very slight movement of the treadle. But the chief point of interest in
this device lies in the combination with the lever of a brake, enabling the
operator, by a simple reversal of the treadle's motion, to instantly
suspend the rotation of the machine. The forked lever, in fact, acts
simultaneously in throwing off the motion and applying the brake. The speed
is always in direct proportion to the pressure exerted upon the treadle,
and a single stitch can be made at will. Fig. 14 shows the friction wheel
separated, the portion a being fast, and e loose.
[Illustration: FIG. 13.]
[Illustration: FIG. 14.]
The Wheeler & Wilson company do not confine themselves to any particular
controller, but prefer the form shown here this evening (Fig. 15), in which
two bands and an intermediate pulley are employed. The first band is left
rather loose, and the machine is set in motion by the tightening of this
band through the depression of the treadle. The speed varies in proportion
to the pressure applied, and the sensitiveness of the arrangement is
increased by a brake device coming into play by the reversal of the treadle
as before.
[Illustration: FIG. 15.]
Messrs. Willcox & Gibbs depend upon a similar device shown in three
varieties to-night.
_Speed of Power Sewing Machines_.--The fastest practicable speed of a
machine worked by the foot appears to be 1,000 stitches per minute. Most
operators can guide the work at a much higher rate, especially in tailoring
or on long seams. The average speed upon such work is 1,200 stitches per
minute; but many lock-stitch machines are run at 1,500 and 1,800 per
minute, and even at much higher rates. There is always a limit to be
imposed upon speed by the guiding powers of hand and eye; it is this limit,
and not the capability of the machine, that confines the rate of driving.
Willcox & Gibbs' single thread machines are run in many instances at 3,500
stitches per minute. We have before us a single thread Singer machine
(appropriately named the "Lightning Sewer") and a Willcox machine, moving
at the enormous rate of 4,500 stitches per minute, and producing good work.
But it is doubtful whether such very great velocities can ever be
advantageously employed. Upon collar work, and in sewing boot uppers, the
rate seldom rises above 1,200 with advantage. If the machines be speeded
too high in any trade, the operator never uses the excess, and it only
proves a drawback. I seen the heaviest and hardest kind of navy boots
stitched at 1,500 to the minute upon Singer's lock-stitch machines. Wheeler
& Wilson's No. 10 D machine has been run by them, I am informed, as high as
2,500 to the minute. Loop-stitch machines, when well made, can be actually
run as high as 6,000, but 4,500 is, I believe, the maximum yet used for
this class of machine, even experimentally. There can be no doubt that
lock-stitch machines can be run as high as 3,000. The actual speeds of the
lock-stitch machines shown here upon the power stand average 1,300; those
of the chain stitch machines vary from 1,200 for the sack sewing machine to
4,500 for the small or single chain stitchers. Any of the latest styles of
either lock stitch or single thread machines can be run far faster than any
known expert operator can possibly guide the work under it.
It is very improbable that such speeds will ever be exceeded. The limit has
no doubt been reached. Very high speed is generally a delusion, and either
results in indifferent work, or actually retards its progress. Some idea of
the speed of the single thread machines now shown may be gathered from the
fact that, running at 4,500, and making eight stitches to the inch, they
accomplish over fourteen yards of sewing every minute.
Of special machines of interest, and which are too unwieldy to be shown
here, I am enabled to exhibit a few photographs.
One of the most novel of these is the "Twin" machine, designed by the
Singer company for the connecting together of the Jacquard cards used in
lace machines. The operation was formerly performed by hand. It is now done
by machine at less cost. The cards are placed upon a feeding drum, and fed
beneath a pair of needles. The laces forming the connection between the
cards are fed above and beneath, in line with the needles, and the whole is
easily stitched together. An extension of the same device is the multiple
machine, in which four needles and shuttles are used, sewing all the four
seams at one operation. This method of linking the cards is considered
better than similar work done by hand.
Of Wheeler & Wilson's new factory, at Bridgeport, and of the Singer
company's great new factory near Glasgow, I am enabled to exhibit
photographic views.
Before drawing my remarks to a close, I would briefly indicate the nature
of the various machines shown upon the power benching. Of the Singer
system, there are four. A drop-feed oscillating shuttle machine for
manufacturing purposes; a wheel-feed oscillating shuttle machine, furnished
with a trimmer, used chiefly in stitching leather and boot uppers; double
chain-stitch machine, used for sack making, now shown for the first time;
and a single thread "Lightning Sewer," fitted with a trimmer for hosiery
work. Of Wheeler & Wilson's system, there is a drop-feed manufacturing
machine with the new detached hook and latest improvements; a No. 10
machine with the usual hook, a wheel feed and trimmer, and a smaller
machine of the same type with drop feed. Of Willcox & Gibbs' system, there
is the ordinary single-thread machine for manufacturing, a single-thread
machine, with a trimmer, as used in the hosiery trades, and a machine
specially used for straw hat making.
We have here a small Singer machine, riding upon the edge of two pieces of
carpet, a carpet machine weighing ten pounds. When the handle is turned, it
stitches and travels over the edges, uniting them faster and more securely
than six hand sewers; and several others, representative of the family type
of sewing machine, besides Wheeler & Wilson's hemstitch machine, the
working of which is of much interest.
I would now invite those of you who seek a better acquaintance with those
curious and novel machines to freely examine and test the various types to
be found upon the power benching and upon stands. One or two operators will
come forward and show some of the capabilities of the machines upon actual
work, in which the making of a straw hat will perhaps show what can be done
in a few minutes by quick speed and expert fingers; but these performances
must not be regarded in the light of competitive tests between the
manufacturers showing them, and are intended merely to show the utility of
motive power driving.
In conclusion, I desire to thank those gentlemen at the head of the leading
firms of sewing machine manufacturers for the trouble they have taken to
arrange for your inspection specimens of their excellent systems, and I
have much satisfaction in expressing my obligations to them for ready
assistance in the preparation of my paper.
* * * * *
Power machines and treadle machines were exhibited by Messrs. Willcox &
Gibbs, Messrs. Wheeler & Wilson, and the Singer Manufacturing Company. The
motive power was provided by an electrical motor, supplied by Mr. Moritz
Immish. The Howe Machine Company exhibited a model of the first machine
made by Elias Howe, and also one of the most recent Howe machines. Mr.
Newton Wilson showed a model of the Saint sewing machines, constructed from
Thomas Saint's patent specification, 1790, and Mr. Carver showed the
Standard sewing machine.
* * * * *
THE NEW KRUPP GUNS.
Nothing is being talked about at present in Germany but the guns of great
caliber that are manufacturing at the celebrated works on the banks of the
Ruhr. As our neighbors appear to be elated over this wonderful work, it is
expedient to examine the subject, in order to see whether their applause is
legitimate.
We have known for a long time that the artillery _materiel_ devoted to the
defense of the German coasts consists of a long, stationary 53/4 inch gun; of
long 73/4 inch hooped steel guns, closed by a cylindrico-prismatic wedge; of
an 8 inch mortar; and of guns of 113/4 and 15 inch caliber. The 113/4 inch gun
is 22 feet in length, and, including the closing mechanism, weighs 79,200
pounds. As regards the projectiles that this weapon throws, the _ordinary_
shell is 33 inches in length, and weighs, all charged, 656 pounds, and the
_exploding_ shell, of the same length, weighs, all charged, 1,160 pounds.
The initial velocity of the latter is 1,600 feet with a maximum charge of
148 pounds of powder.
The 15 inch gun is 32.8 feet in length, and weighs 158,400 pounds. Its
projectiles are 3.67 feet in length. The _ordinary_ shell, charge included,
weighs 1,400 pounds, and the exploding shell, under the same circumstances,
1,700 pounds, that is, more than three quarters of a metric ton. The
initial velocity of this last named projectile is 1,650 feet with a maximum
charge of 1,650 pounds of powder. We also know that Mr. Krupp has two
models of guns of 131/2 inch caliber, and of a length equal to 35 times the
caliber, say 39-5/12 feet. The lighter of these models (which was shown at
Anvers) weighs no less than 264,000 pounds, carriage not included. Its
cylindrico prismatic closing mechanism (_Rundkeilverschluss_) alone weighs
82,500 pounds. This is the weight of a 53/4 inch hooped steel gun!
[Illustration: FIG. 1.--NEW 52 FOOT KRUPP GUN AND A GERMAN FIELD PIECE
FIGURED ON THE SAME SCALE.]
We now learn that the Essen works have just begun the manufacture of a
314,600 pound gun. This piece, called "40 cm. kanone L/40," will, of
course, be of 15.6 inch caliber, but it will differ from the one above
described in that its length will be equal to 40 times the caliber, say 52
feet, or to the space occupied on the maneuvering ground by a field piece
drawn by six horses (Fig. 1). This gun will be provided with two kinds of
projectiles. One of these, called _light_, will be 31/2 feet in length, weigh
1,628 pounds, and be capable of taking an initial velocity of 2,410 feet
and of piercing, on its exit from the chamber, either a hammered iron plate
33/4 feet in thickness or two united plates 13/4 and 23/4 feet in thickness.
The shell called _heavy_ will be 53/4 feet in length, and weigh 2,310 pounds,
say more than a 43/4 inch siege piece! The charge employed will be 1,067
pounds of brown, prismatic Dunwald powder. Ten hundred and sixty-seven
pounds--nearly half a metric ton, more than the weight of a field piece
without its carriage! With this enormous charge, the heavy shell will be
capable of an initial velocity of 2,100 feet and of piercing, on its exit
from the chamber, either a hammered iron plate 4 feet in thickness or two
united plates 2 and 2.88 feet in thickness.
The _Cologne Gazette_, from which we borrow most of the data just
presented, adds that the "40 L/40" piece will be the largest cannon in the
world, but that it will not long enjoy the privilege of such pre-eminence.
It appears, in fact, that Mr. Krupp is preparing to manufacture a gun of
171/2 inch caliber, weighing 330,000 pounds. The projectile for this monster
will be 6 feet in length, say the stature of a full grown man, and will
weigh no less than a ton and a half. A man of medium stature will measure a
little less than this projectile (Fig. 2).
It is possible that all these figures have been slightly exaggerated by the
ultra-Vosges journals, who doubtless intend to make an impression upon us;
but we shall not dwell upon that point.
As regards the penetrating power of the large "40 L/40" gun, the German
press observes that in 1868 artillery was incapable of piercing in
one-hundredths of an inch what it is now piercing in tenths of an inch. The
principle was formerly admitted, it says, that a shell should by right have
a thickness equal to its caliber. Now, "the largest cannon in the world"
perforates a plate whose thickness is three times the diameter of the gun's
bore. What great progress! exclaim the German journals, and how jealous the
French and English are going to be! Jealous of that? Why, indeed? We are
not the least in the world so. How could we be? In the first place, we have
a gun of very great caliber--a 131/4 inch steel coast and siege piece. This
weighs 37 tons, and is 363/4 feet in length. Its projectile weighs from 924
to 1,320 pounds, according to its internal organization. Its conoid head is
very elongated, and by reason of this elegant form it always falls upon its
point, even at falling angles of an amplitude approaching 60 degrees. The
charge used varies from 396 to 440 pounds, according to the nature of the
powder. As for the ballistic properties of the piece, they are very
remarkable. Its projectile has an initial velocity of 2,132 feet, and the
maximum range is from 10 to 11 miles, say the distance from Paris to
Montgeron by the Paris-Lyons-Mediterranean railroad, or from Paris to
Versailles. Finally, the accuracy of this gun is much greater than that of
the 91/2 inch steel one. Now, the accuracy of this latter is such that it is
impossible for its projectiles to miss a ship under way, and that we are
sure of playing with it against the enemy that game whose device is "We win
at every shot!" Well, we do not hesitate to say that these results appear
to us to be satisfactory--we mean quite sufficient--and that there is no
need of looking for a better gun. If there were, French industry would be
capable of producing weapons of any caliber desired. As regards this, there
is, so to speak, no limit; moreover, taking into account merely the
terrestrial conditions of the problem, we may be satisfied that the great
works of our country are more powerfully equipped than those of Essen, and
consequently better able to forge large pieces of steel.
Mr. Krupp, it is said, is very proud of his two power hammers, which he has
named Max and Fritz. But, on the whole, these two apparatus are only fifty
ton ones, and have a fall of but ten feet. Now, Creusot and St. Chamond
each has a hundred ton steam hammer with a fall of 16 feet, accompanied
with four furnaces and four cranes.
[Illustration: FIG. 2.--3,300 POUND PROJECTILE OF A KRUPP GUN IN COURSE
OF MANUFACTURE.]
But why proceed to the manufacture of monstrous guns, like those that Mr.
Krupp has just produced, or meditates producing in the future; guns of such
a caliber can be used only in special cases--in battery on the coast or on
board of a ship. It is not with _materiel_ of this kind that war is waged;
it is with field pieces. Our ultra-Vosges neighbors well know this.
One of the reasons that the war that very recently threatened us did not
break out, was because the Germans could not fail to see that their field
_materiel_ was not as powerful as ours; that the shell of our 31/2 inch gun
weighs 171/2 pounds, while that of their heavy 31/2 inch gun does not weigh 15.
Now, this difference has its value.
Hunters well know what importance it is necessary to attach to the number
of the ball that they use.
This granted, it is well to observe that the net cost of the "40 cm. kanone
L/40" must not be less than $300,000 or $400,000. Now, on the interest of
such a sum we could have from ten to fifteen complete batteries, that is to
say, comprising, in addition to the sixty or eighty guns, all the necessary
accessories, such as carriages, limbers, caissons, harness, etc.
Frankly, between the two acquisitions, there is no hesitation possible.
Finally, if we must say so, we do not think that foreign powers, when they
believe it their duty to provide themselves with _materiel_ of great
caliber, will think of supplying themselves from the Essen works, on
account of the memorable accidents due to the imperfection of guns coming
from this celebrated establishment. The list of burstings that have
occurred, not only in Germany, but also in Russia, Bohemia, Italy, Turkey,
and Roumania, is already a long one. To speak here only of what occurred
in France in 1870-71, it is certain that out of seventy German guns of
large caliber in battery against the southwest front of the wall of Paris,
thirty-six--say more than half--were put out of service during the first
fifteen days of the bombardment, and that too through firing merely; and it
was the opinion of Mr. De Moltke himself that the German siege batteries
would have been reduced to silence, had the defenders been able to hold out
for a week longer. It is equally certain that, during the course of the
Loire campaign, eighty guns of Prince Frederick Charles' were put out of
service by the sole fact of their firing. Summing up the history of these
many accidents, the Duke of Cambridge asserted to the House of Lords (April
30, 1876) that _two hundred_ Krupp guns burst during the Franco-German war.
Have the engineers of the Essen works improved their processes of
manufacture since that epoch? It is permissible to doubt it, seeing that,
very recently, the Italian navy refused to take from Mr. Krupp some 151/2
inch guns whose tubes were but very imperfectly welded.
Must the numerous accidents mentioned be attributed to defects in the metal
employed? Were they due to defective hooping? Were they due to some one of
the numerous inconveniences inherent to the cylindrico-prismatic system of
closing (_Rundkeilverschluss_)?
They were doubtless owing to such causes combined.--_La Nature_.
* * * * *
COLORS OF THIN PLATES.
Back to Full Books
|