Scientific American Supplement, No. 385, May 19, 1883
by
Various
Part 1 out of 2
Produced by Don Kretz, Juliet Sutherland, and Distributed Proofreaders
[Illustration]
SCIENTIFIC AMERICAN SUPPLEMENT NO. 385
NEW YORK, MAY 19, 1883
Scientific American Supplement. Vol. XV., No. 385.
Scientific American established 1845
Scientific American Supplement, $5 a year.
Scientific American and Supplement, $7 a year.
* * * * *
TABLE OF CONTENTS.
I. NATURAL HISTORY.--Fishes of Cuban Waters.
Panax Victoriae.--1 Illustration.
A Note on Sap. By Prof. ATTFIELD.
The Crow.--Illustration.
The Praying Mantis and its Allies.--Illustration.
May Flies.--2 illustrations.
II. TECHNOLOGY.--A Quick Way to Ascertain the Focus
of a Lens.--1 diagram.
The History of the Pianoforte. By A.J.
HIPKINS.--Different parts of a pianoforte and
their uses.--Inventor of the instrument and his
"action."--First German piano-maker.--Square
pianos.--Pianos of Broadwood, Backers, Stodart,
and Erard.--Introduction of metal tubes, plates,
bars, and frames.--Improvements of Meyer, the
Steinways, Chickerings, and others.--Upright
pianos.--Several figures.
III. MEDICINE AND HYGIENE.--The Poisonous Properties of
Nitrate of Silver and a Recent Case of Poisoning
with the Same. By H. A. MOTT, Jr.
Tubercle Bacilli in Sputa.
Malaria. By Dr. JAMES H. SALISBURY.--VIII. Local
observations.--Effect of the sun on ague
plants.--Investigations into the cause of
ague.--Notes on marsh miasm.--Analysis of malari a
plant.--Numerous figures.
IV. ENGINEERING.--Torpedo Boats.--Full page illustration.
Pictet's High Speed Boat.--Several figures and
diagrams.
Initial Stability Indicator for Ships.--4 figures.
V. ELECTRICITY, LIGHT, AND HEAT.--Scrivanow's Chloride of
Silver Pile.--2 figures.
On the Luminosity of Flame.
VI. CHEMISTRY.--New Bleaching Process, with Regeneration of
the Baths Used. By M. BONNEVILLE.
Detection of Magenta, Archil, and Cudbear in Wine.
VII. ARCHITECTURE.--The Pantheon at Rome.
VIII. MISCELLANEOUS.--The Raphael Celebration at
Rome.--3 Illustrations.
Great International Fisheries Exhibition.--1 figure.
Puppet Shows among the Greeks.--3 illustrations.
* * * * *
THE RAPHAEL CELEBRATION AT ROME.
The most famous of Italian painters, Raffaele Sanzio, whom the world
commonly calls Raphael, was born at Urbino, in Umbria, part of the Papal
States, four hundred years ago. The anniversary was celebrated, on March
28, 1883, both in that town and in Rome, where he lived and worked, and
where he died in 1520, with processions, orations, poetical recitations,
performances of music, exhibitions of pictures, statues, and busts,
visits to the tomb of the great artist in the Pantheon, and with
banquets and other festivities. The King and Queen of Italy were present
at the Capitol of Rome (the Palace of the City Municipality) where one
part of these proceedings took place.
[Illustration: SKELETON OF RAPHAEL AS FOUND IN HIS TOMB IN THE PANTHEON,
IN 1833.]
At ten o'clock in the morning a procession set forth from the Capitol to
the Pantheon, to render homage at the tomb of Raphael. It was arranged
in the following order: Two Fedeli, or municipal ushers, in picturesque
costumes of the sixteenth century, headed the procession, carrying two
laurel wreaths fastened with ribbons representing the colors of Rome,
red and dark yellow; a company of Vigili, the Roman firemen; the
municipal band; the standard of Rome, carried by an officer of the
Vigili; and the banners of the fourteen quarters of the city. Then came
the Minister of Public Instruction and the Minister of Public Works; the
Syndic of Rome, Duke Leopoldo Torlonia; and the Prefect of Rome, the
Marquis Gravina. The members of the communal giunta, the provincial
deputation, and the communal and provincial council followed the
principal authorities. Next in order came the presidents of Italian and
foreign academies and art institutions, the president of the academy of
the Licei, the representatives of all the foreign academies, the members
of the academy of St. Luke, the general direction of antiquities, the
members of the Permanent Commission of Fine Arts, the members of the
Communal Archaeological Commission, the guardians of the Pantheon, the
members of the International Artistic Club, presided over by Prince
Odescalchi; the members of the art schools, the pupils of the San
Michele and Termini schools with their bands, the pupils of the
elementary and female art schools. The procession was rendered more
interesting by the presence of many Italian and foreign artists. Having
arrived at the Pantheon, the chief personages took their place in front
of Raphael's tomb. Every visitor to Rome knows this tomb, which is
situated behind the third chapel on the left of the visitor entering the
Pantheon. The altar was endowed by Raphael, and behind it is a picture
of the Virgin and Child, known as the Madonna del Sasso, which was
executed at his request and was produced by Lorenzo Lotto, a friend and
pupil of the great painter. Above the inscription usually hang a few
small pictures, which were presented by very poor artists who thought
themselves cured by prayers at the shrine. This is confirmed by a crutch
hanging up close to the pilaster. The bones of Raphael are laid in this
tomb since 1520, with an epitaph recording the esteem in which he was
held by Popes Julius II. and Leo X.; but they have not always been
allowed to lie undisturbed. On Sept. 14, 1833, the tomb was opened to
inspect the mouldering skeleton, of which drawings were made, and are
reproduced in two of our illustrations. The proceedings at the tomb in
the recent anniversary visit were brief and simple; a number of laurel
or floral wreaths were suspended there, one sent by the president and
members of the Royal Academy of London; and the Syndic of Rome unveiled
a bronze bust of Raphael, which had been placed in a niche at the side.
[Illustration: THE ANCIENT ROMAN TEMPLE NOW KNOWN AS THE PANTHEON, AT
ROME.]
This ceremony at the Pantheon was concluded by all visitors writing
their names on two albums which had been placed near Victor Emmanuel's
tomb and Raphael's tomb. The commemoration in the hall of the Horatii
and Curiatii in the Capitol was a great success, their Majesties, the
Ministers, the members of the diplomatic body, and a distinguished
assembly being present. Signor Quirino Leoni read an admirable discourse
on Raphael and his times.
The ancient city of Urbino, Raphael's birthplace, has fallen into
decay, but has remembered its historic renown upon this occasion.
The representatives of the Government and municipal authorities, and
delegates of the leading Italian cities went in procession to visit the
house where Raphael was born. Commemoration speeches were pronounced
in the great hall of the ducal palace by Signor Minghetti and Senator
Massarani. The commemoration ended with a cantata composed by Signor
Rossi. The Via Raffaelle was illuminated in the evening, and a gala
spectacle was given at the Sanzio Theater. Next day the exhibition of
designs for a monument to Raphael was inaugurated at Urbino, and at
night a great torchlight procession took place.--_Illustrated London
News_.
[Illustration: RAPHAEL'S TOMB IN THE PANTHEON, AT ROME.]
* * * * *
THE PANTHEON AT ROME.
The edifice known as the Pantheon, in Rome, is one of the best preserved
specimens of Roman architecture. It was erected in the year 26 B.C.,
and is therefore now about one thousand nine hundred years old. It was
consecrated as a Christian church in the year 608. Its rotunda is 143
ft. in diameter and also 143 ft. high. Its portico is remarkable for the
elegance and number of its Corinthian columns.
* * * * *
Senor Felipe Poey, a famous ichthyologist of Cuba, has recently brought
out an exhaustive work upon the fishes of Cuban waters, in which he
describes and depicts no fewer than 782 distinct varieties, although he
admits some doubts about 105 kinds, concerning which he has yet to get
more exact information. There can be no question, however, he claims,
about the 677 species remaining, more than half of which he first
described in previous works upon this subject, which has been the study
of his life.
* * * * *
THE GREAT INTERNATIONAL FISHERIES EXHIBITION.
Her Majesty the Queen has appointed the 12th of May for the opening
of the International Fisheries Exhibition, which an influential and
energetic committee, under the active presidency of the Prince of Wales,
had developed to a magnitude undreamt of by those concerned in its early
beginnings.
The idea of an _international_ Fisheries Exhibition arose out of the
success of the show of British fishery held at Norwich a short time ago;
and the president and executive of the latter formed the nucleus of the
far more powerful body by whom the present enterprise has been brought
about.
The plan of the buildings embraces the whole of the twenty-two acres of
the Horticultural Gardens; the upper half, left in its usual state of
cultivation, will form a pleasant lounge and resting place for visitors
in the intervals of their study of the collections. This element of
garden accommodation was one of the most attractive features at the
Paris Exhibition of 1878.
As the plan of the buildings is straggling and extended, and widely
separates the classes, the most convenient mode of seeing the show will
probably be found by going through the surrounding buildings first, and
then taking the annexes as they occur.
[Illustration: THE INTERNATIONAL FISHERIES EXHIBITION, LONDON.
BLOCK PLAN.--A, Switzerland; B, Isle of Man; C, Bahamas and W.I.
Islands; D, Hawaii; E, Poland; F, Portugal; G, Austria; H, Germany; I,
France; J, Italy; K, Greece; L, China; M, India and Ceylon; N, Straits
Settlements; O, Japan; P, Tasmania; Q, New South Wales.--Scale 200 feet
to the inch.]
On entering the main doors in the Exhibition Road, we pass through the
Vestibule to the Council Room of the Royal Horticultural Society,
which has been decorated for the reception of marine paintings, river
subjects, and fish pictures of all sorts, by modern artists.
Leaving the Fine Arts behind, the principal building of the Exhibition
is before us--that devoted to the deep sea fisheries of Great Britain.
It is a handsome wooden structure, 750 feet in length, 50 feet wide, and
30 feet at its greatest height. The model of this, as well as of the
other temporary wooden buildings, is the same as that of the annexes of
the great Exhibition of 1862.
On our left are the Dining Rooms with the kitchens in the rear. The
third room, set apart for cheap fish dinners (one of the features of the
Exhibition), is to be decorated at the expense of the Baroness Burdett
Coutts, and its walls are to be hung with pictures lent by the
Fishmongers' Company, who have also furnished the requisite chairs and
tables, and have made arrangements for a daily supply of cheap fish,
while almost everything necessary to its maintenance (forks, spoons,
table-linen, etc.) will be lent by various firms.
The apsidal building attached is to be devoted to lectures on the
cooking of fish.
Having crossed the British Section, and turning to the right and passing
by another entrance, we come upon what will be to all one of the most
interesting features of the Exhibition, and to the scientific student
of ichthyology a collection of paramount importance. We allude to the
Western Arcade, in which are placed the Aquaria, which have in their
construction given rise to more thoughtful care and deliberation than
any other part of the works. On the right, in the bays, are the twenty
large asphalt tanks, about 12 feet long, 3 feet wide, and 3 feet deep.
These are the largest dimensions that the space at command will allow,
but it is feared by some that it will be found somewhat confined for
fast going fish. Along the wall on the left are ranged twenty smaller or
table tanks of slate, which vary somewhat in size; the ten largest are
about 5 feet 8 inches long, 2 feet 9 inches wide, and 1 foot 9 inches
deep.
In this Western Arcade will be found all the new inventions in fish
culture--models of hatching, breeding, and rearing establishments,
apparatus for the transporting of fish, ova, models and drawings of
fish-passes and ladders, and representations of the development and
growth of fish. The chief exhibitors are specialists, and are already
well known to our readers. Sir James Gibson Maitland has taken an active
part in the arrangement of this branch, and is himself one of the
principal contributors.
In the north of the Arcade, where it curves toward the Conservatory,
will be shown an enormous collection of examples of stuffed fish,
contributed by many prominent angling societies. In front of these on
the counter will be ranged microscopic preparations of parasites,
etc., and a stand from the Norwich Exhibition of a fauna of fish and
fish-eating birds.
Passing behind the Conservatory and down the Eastern Arcade--in which
will be arranged algae, sponges, mollusca, star-fish, worms used for
bait, insects which destroy spawn or which serve as food for fish,
etc.--on turning to the left, we find ourselves in the fish market,
which will probably vie with the aquaria on the other side in attracting
popular attention. This model Billingsgate is to be divided into two
parts, the one for the sale of fresh, the other of dried and cured fish.
Next in order come the two long iron sheds appropriated respectively to
life-boats and machinery in motion. Then past the Royal pavilion (the
idea of which was doubtless taken from its prototype at the Paris
Exhibition) to the southern end of the central block, which is shared
by the Netherlands and Newfoundland; just to the north of the former
Belgium has a place.
While the Committee of the Netherlands was one of the earliest formed,
Belgium only came in at the eleventh hour; she will, however, owing
to the zealous activity of Mr. Lenders, the consul in London, send
an important contribution worthy of her interest in the North Sea
fisheries. We ought also to mention that Newfoundland is among those
colonies which have shown great energy, and she may be expected to send
a large collection.
Passing northward we come to Sweden and Norway, with Chili between them.
These two countries were, like the Netherlands, early in preparing to
participate in the Exhibition. Each has had its own committee, which has
been working hard since early in 1882.
Parallel to the Scandinavian section is that devoted to Canada and the
United States, and each will occupy an equal space--ten thousand square
feet.
In the northern Transept will be placed the inland fisheries of the
United Kingdom. At each end of the building is aptly inclosed a basin
formerly standing in the gardens: and over the eastern one will be
erected the dais from which the Queen will formally declare the
Exhibition open.
Shooting out at right angles are the Spanish annex, and the building
shared by India and Ceylon. China and Japan and New South Wales; while
corresponding to those at the western end are the Russian annex, and a
shed allotted to several countries and colonies. The Isle of Man, the
Bahamas, Switzerland, Germany, Hawaii, Italy, and Greece--all find their
space under its roof.
After all the buildings were planned, the Governments of Russia and
Spain declared their intention of participating; and accordingly for
each of these countries a commodious iron building has been specially
erected.
The Spanish collection will be of peculiar interest; it has been
gathered together by a Government vessel ordered round the coast for the
purpose, and taking up contributions at all the seaports as it passed.
Of the countries whose Governments for inscrutable reasons of state show
disfavor and lack of sympathy, Germany is prominent; although by the
active initiative of the London Committee some important contributions
have been secured from private individuals; among them, we are happy to
say, is Mr. Max von dem Borne, who will send his celebrated incubators,
which the English Committee have arranged to exhibit in operation at
their own expense.
Although the Italian Government, like that of Germany, holds aloof,
individuals, especially Dr. Dohrn, of the Naples Zoological Station,
will send contributions of great scientific value.
In the Chinese and Japanese annex, on the east, will be seen a large
collection of specimens (including the gigantic crabs), which have been
collected, to great extent, at the suggestion of Dr. Guenther, of the
British Museum.
It is at the same time fortunate and unfortunate that a similar
Fisheries Exhibition is now being held at Yokohama, as many specimens
which have been collected specially for their own use would otherwise be
wanting; and on the other hand, many are held back for their own show.
China, of all foreign countries, was the first to send her goods, which
arrived at the building on the 30th of March, accompanied by native
workmen who are preparing to erect over a basin contiguous to their
annex models of the summer house and bridge with which the willow
pattern plate has made us familiar; while on the basin will float models
of Chinese junks.
Of British colonies, New South Wales will contribute a very interesting
collection placed under the care of the Curator of the Sydney Museum;
and from the Indian Empire will come a large gathering of specimens in
spirits under the superintendence of Dr. Francis Day.
Of great scientific interest are the exhibits, to be placed in two
neighboring sheds, of the Native Guano Company and the Millowners'
Association. The former will show all the patents used for the
purification of the rivers from sewage, and the latter will display in
action their method of rendering innocuous the chemical pollutions which
factories pour into the river.
In the large piece of water in the northern part of the gardens, which
has been deepened on purpose, apparatus in connection with diving will
be seen; and hard by, in a shed, Messrs. Siebe, Gorman & Co. will show
a selection of beautiful minute shells dredged from the bottom of the
Mediterranean.
In the open basins in the gardens will be seen beavers, seals,
sea-lions, waders, and other aquatic birds.
From this preliminary walk round enough has, we think, been seen to show
that the Great International Fisheries Exhibition will prove of interest
alike to the ordinary visitor, to those anxious for the well-being
of fishermen, to fishermen themselves of every degree, and to the
scientific student of ichthyology in all its branches.--_Nature_.
* * * * *
PUPPET SHOWS AMONG THE GREEKS.
The ancients, especially the Greeks, were very fond of theatrical
representations; but, as Mr. Magnin has remarked in his _Origines du
Theatre Moderne_, public representations were very expensive, and for
that very reason very rare. Moreover, those who were not in a condition
of freedom were excluded from them; and, finally, all cities could not
have a large theater, and provide for the expenses that it carried with
it. It became necessary, then, for every day needs, for all conditions
and for all places, that there should be comedians of an inferior order,
charged with the duty of offering continuously and inexpensively the
emotions of the drama to all classes of inhabitants.
Formerly, as to-day, there were seen wandering from village to village
menageries, puppet shows, fortune tellers, jugglers, and performers of
tricks of all kinds. These prestidigitators even obtained at times such
celebrity that history has preserved their names for us--at least of two
of them, Euclides and Theodosius, to whom statues were erected by their
contemporaries. One of these was put up at Athens in the Theater of
Bacchus, alongside of that of the great writer of tragedy, AEschylus, and
the other at the Theater of the Istiaians, holding in the hand a small
ball. The grammarian Athenaeus, who reports these facts in his "Banquet
of the Sages," profits by the occasion to deplore the taste of the
Athenians, who preferred the inventions of mechanics to the culture of
mind and histrions to philosophers. He adds with vexation that Diophites
of Locris passed down to posterity simply because he came one day to
Thebes wearing around his body bladders filled with wine and milk,
and so arranged that he could spurt at will one of these liquids in
apparently drawing it from his mouth. What would Athenaeus say if he knew
that it was through him alone that the name of this histrion had come
down to us?
[Illustration: FIG. 1.--THE MARVELOUS STATUE OF CYBELE.]
Philo, of Byzantium, and Heron, of Alexandria, to whom we always have
to have recourse when we desire accurate information as to the mechanic
arts of antiquity, both composed treatises on puppet shows. That of
Philo is lost, but Heron's treatise has been preserved to us, and has
recently been translated in part by Mr. Victor Prou.
According to the Greek engineer, there were several kinds of puppet
shows. The oldest and simplest consisted of a small stationary case,
isolated on every side, in which the stage was closed by doors that
opened automatically several times to exhibit the different tableaux.
The programme of the representation was generally as follows: The first
tableau showed a head, painted on the back of the stage, which moved
its eyes, and lowered and raised them alternately. The door having been
closed, and then opened again, there was seen, instead of the head, a
group of persons. Finally, the stage opened a third time to show a new
group, and this finished the representation. There were, then, only
three movements to be made, that of the doors, that of the eyes, and
that of the change of background.
As such representations were often given on the stages of large
theaters, a method was devised later on of causing the case to start
from the scenes behind which it was bidden from the spectators, and of
moving automatically to the front of the stage, where it exhibited in
succession the different tableaux; after which it returned automatically
behind the scenes. Here is one of the scenes indicated by Heron,
entitled the "Triumph of Bacchus":
The movable case shows, at its upper part, a platform from which arises
a cylindrical temple, the roof of which, supported by six columns, is
conical and surmounted by a figure of Victory with spread wings and
holding a crown in her right hand. In the center of the temple Bacchus
is seen standing, holding a thyrsus in his left hand, and a cup in his
right. At his feet lies a panther. In front of and behind the god, on
the platform of the stage, are two altars provided with combustible
material. Very near the columns, but external to them, there are
bacchantes placed in any posture that may be desired. All being thus
prepared, says Heron, the automatic apparatus is set in motion. The
theater then moves of itself to the spot selected, and there stops. Then
the altar in front of Jupiter becomes lighted, and, at the same time,
milk and water spurt from his thyrsus, while his cup pours wine over the
panther. The four faces of the base become encircled with crowns, and,
to the noise of drums and cymbals, the bacchantes dance round about the
temple. Soon, the noise having ceased, Victory on the top of the temple,
and Bacchus within it, face about. The altar that was behind the god
is now in front of him, and becomes lighted in its turn. Then occurs
another outflow from the thyrsus and cup, and another round of the
bacchantes to the sound of drums and cymbals. The dance being finished,
the theater returns to its former station. Thus ends the apotheosis.
I shall try to briefly indicate the processes which permitted of these
different operations being performed, and which offer a much more
general interest than one might at first sight be led to believe; for
almost all of them had been employed in former times for producing the
illusions to which ancient religions owed their power.
The automatic movement of the case was obtained by means of
counterpoises and two cords wound about horizontal bobbins in such a way
as to produce by their winding up a forward motion in a vertical plane,
and subsequently a backward movement to the starting place. Supposing
the motive cords properly wound around vertical bobbins, instead of a
horizontal one, and we have the half revolution of Bacchus and Victory,
as well as the complete revolution of the bacchantes.
The successive lighting of the two altars, the flow of milk and wine,
and the noise of drums and cymbals were likewise obtained by the aid of
cords moved by counterpoises, and the lengths of which were graduated
in such a way as to open and close orifices, at the proper moment, by
acting through traction on sliding valves which kept them closed.
Small pieces of combustible material were piled up beforehand on the two
altars, the bodies of which were of metal, and in the interior of which
were hidden small lamps that were separated from the combustible by a
metal plate which was drawn aside at the proper moment by a small
chain. The flame, on traversing the orifice, thus communicated with the
combustible.
The milk and wine which flowed out at two different times through the
thyrsus and cup of Bacchus came from a double reservoir hidden under the
roof of the temple, over the orifices. The latter communicated, each of
them, with one of the halves of the reservoir through two tubes inserted
in the columns of the small edifice. These tubes were prolonged under
the floor of the stage, and extended upward to the hands of Bacchus. A
key, maneuvered by cords, alternately opened and closed the orifices
which gave passage to the two liquids.
As for the noise of the drums and cymbals, that resulted from the
falling of granules of lead, contained in an invisible box provided with
an automatic sliding-valve, upon an inclined tambourine, whence they
rebounded against little cymbals in the interior of the base of the car.
[Illustration: FIG. 2.--MARVELOUS ALTAR (According to Heron).]
Finally, the crowns and garlands that suddenly made their appearance on
the four faces of the base of the stage were hidden there in advance
between the two walls surrounding the base. The space thus made for the
crowns was closed beneath, along each face, by a horizontal trap moving
on hinges that connected it with the inner wall of the base, but which
was held temporarily stationary by means of a catch. The crowns were
attached to the top of their compartment by cords that would have
allowed them to fall to the level of the pedestal, had they not been
supported by the traps.
At the desired moment, the catch, which was controlled by a special
cord, ceased to hold the trap, and the latter, falling vertically, gave
passage to the festoons and crowns that small leaden weights then drew
along with all the quickness necessary.
Two points here are specially worthy of attracting our attention, and
these are the flow of wine or milk from the statue of Bacchus, and
the spontaneous lighting of the altar. These, in fact, were the two
illusions that were most admired in ancient times, and there were
several processes of performing them. Father Kircher possessed in his
museum an apparatus which he describes in _Oedipus Egyptiacus_ (t. ii.,
p. 333), and which probably came from some ancient Egyptian temple.
(Fig. 1.)
It consisted of a hollow hemispherical dome, supported by four columns,
and placed over the statue of the goddess of many breasts. To two of
these columns were adapted movable brackets, at whose extremities there
were fixed lamps. The hemisphere was hermetically closed underneath by a
metal plate. The small altar which supported the statue, and which was
filled with milk, communicated with the interior of the statue by a tube
reaching nearly to the bottom. The altar likewise communicated with
the hollow dome by a tube having a double bend. At the moment of the
sacrifice the two lamps were lighted and the brackets turned so that the
flames should come in contact with and heat the bottom of the dome. The
air contained in the latter, being dilated, issued through the tube, X
M, pressed on the milk contained in the altar, and caused it to rise
through the straight tube into the interior of the statue as high as
the breasts. A series of small conduits, into which the principal tube
divided, carried the liquid to the breasts, whence it spurted out, to
the great admiration of the spectators, who cried out at the miracle.
The sacrifice being ended, the lamps were put out, and the milk ceased
to flow.
Heron, of Alexandria, describes in his _Pneumatics_ several analogous
apparatus. Here is one of them. (We translate the Greek text literally.)
[Illustration: Fig. 3.--MARVELOUS ALTAR (According to Heron).]
"To construct an altar in such a way that, when a fire is lighted
thereon, the statues at the side of it shall make libations. (Fig. 2.)
"Let there be a pedestal. A B [Gamma] [Delta], on which are placed
statues, and an altar, E Z H, closed on every side. The pedestal should
also be hermetically closed, but is communicated with the altar through
a central tube. It is traversed likewise by the tube, e [Lambda] (in
the interior of the statue to the right), not far from the bottom which
terminates in a cup held by the statue, e. Water is poured into the
pedestal through a hole, M, which is afterward corked up.
"If, then, a fire be lighted on the altar, the internal air will be
dilated and will enter the pedestal and drive out the water contained in
it. But the latter, having no other exit than the tube, e [Lambda], will
rise into the cup, and so the statue will make a libation. This will
last as long as the fire does. On extinguishing the fire the libation
ceases, and occurs anew as often as the fire is relighted.
"It is necessary that the tube through which the heat is to introduce
itself shall be wider in the middle; and it is necessary, in fact, that
the heat, or rather that the draught that it produces, shall accumulate
in an inflation in order to have more effect."
According to Father Kircher (_l. c._), an author whom he calls Bitho
reports that there was at Sais a temple of Minerva in which there was an
altar on which, when a fire was lighted, Dyonysos and Artemis (Bacchus
and Diana) poured milk and wine, while a dragon hissed.
It is easy to conceive of the modification to be introduced into the
apparatus above described by Heron, in order to cause the outflow of
milk from one side and of wine from the other.
After having indicated it, Father Kircher adds: "It is thus that Bacchus
and Diana appeared to pour, one of them wine, and the other milk, and
that the dragon seemed to applaud their action by hisses. As the people
who were present at the spectacle did not see what was going on within,
it is not astonishing that they believed it due to divine intervention.
We know, in fact, that Osiris or Bacchus was considered as the
discoverer of the vine and of milk; that Iris was the genius of the
waters of the Nile; and that the Serpent, or good genius, was the first
cause of all these things. Since, moreover, sacrifices had to be made to
the gods in order to obtain benefits, the flow of milk, wine, or water,
as well as the hissing of the serpent, when the sacrificial flame was
lighted, appeared to demonstrate clearly the existence of the gods."
In another analogous apparatus of Heron's, it is steam that performs the
role that we have just seen played by dilated air. But the ancients do
not appear to have perceived the essential difference, as regards motive
power, that exists between these two agents; indeed, their preferences
were wholly for air, although the effects produced were not very great.
We might cite several small machines of this sort, but we shall confine
ourselves to one example that has some relation to our subject. This
also is borrowed from Heron's _Pneumatics_. (Fig. 3.)
"Fire being lighted on an altar, figures will appear to execute a round
dance. The altars should be transparent, and of glass or horn. From the
fire-place there starts a tube which runs to the base of the altar,
where it revolves on a pivot, while its upper part revolves in a tube
fixed to the fire-place. To the tube there should be adjusted other
tubes (horizontal) in communication with it, which cross each other
at right angles, and which are bent in opposite directions at their
extremities. There is likewise fixed to it a disk upon which are
attached figures which form a round. When the fire of the altar is
lighted, the air, becoming heated, will pass into the tube; but being
driven from the latter, it will pass through the small bent tubes and
... cause the tube as well as the figures to revolve."
Father Kircher, who had at his disposal either many documents that we
are not acquainted with, or else a very lively imagination, alleges
(_Oedip. AEg._, t. ii., p. 338) that King Menes took much delight in
seeing such figures revolve.
Nor are the examples of holy fire-places that kindled spontaneously
wanting in antiquity.
Pliny (_Hist. Nat_., ii., 7) and Horace (_Serm., Sat. v._) tell us that
this phenomenon occurred in the temple of Gnatia, and Solin (Ch. V.)
says that it was observed likewise on an altar near Agrigentum.
Athenaeus (_Deipn_. i., 15) says that the celebrated prestidigitator,
Cratisthenes, of Phlius, pupil of another celebrated prestidigitator
named Xenophon, knew the art of preparing a fire which lighted
spontaneously.
Pausanias tells us that in a city of Lydia, whose inhabitants, having
fallen under the yoke of the Persians, had embraced the religion of the
Magi, "there exists an altar upon which there are ashes which, in color,
resemble no other. The priest puts wood on the altar, and invokes I
know not what god by harangues taken from a book written in a barbarous
tongue unknown to the Greeks, when the wood soon lights of itself
without fire, and the flame from it is very clear."
The secret, or rather one of the secrets of the Magi, has been revealed
to us by one of the Fathers of the Church (Saint Hippolytus, it is
thought), who has left, in a work entitled _Philosophumena_, which
is designed to refute the doctrines of the pagans, a chapter on the
illusions of their priests. According to him, the altars on which this
miracle took place contained, instead of ashes, calcined lime and a
large quantity of incense reduced to powder; and this would explain the
unusual color of the ashes observed by Pausanias. The process, moreover,
is excellent; for it is only necessary to throw a little water on the
lime, with certain precautions, to develop a heat capable of setting on
fire incense or any other material that is more readily combustible,
such as sulphur and phosphorus. The same author points out still another
means, and this consists in hiding firebrands in small bells that were
afterward covered with shavings, the latter having previously been
covered with a composition made of naphtha and bitumen (Greek fire).
As may be seen, a very small movement sufficed to bring about
combustion.--_A. De Rochas, in La Nature_.
* * * * *
TORPEDO BOATS.
There are several kinds of torpedoes. The one which is most used in the
French navy is called the "carried" torpedo (_torpille portee_), thus
named because the torpedo boat literally _carries_ it right under the
sides of the enemy's ship. It consists of a cartridge of about 20
kilogrammes of gun cotton, placed at the extremity of an iron rod, 12
meters in length, projecting in a downward direction from the fore part
of the boat. The charge is fired by an electric spark by means of an
apparatus placed in the lookout compartment. Our engraving represents an
attack on an ironclad by means of one of these torpedoes. Under cover of
darkness, the torpedo boat has been enabled to approach without being
disabled by the projectiles from the revolving guns of the man-of-war,
and has stopped suddenly and ignited the torpedo as soon as the latter
came in contact with the enemy's hull.
The water spout produced by the explosion sometimes completely covers
the torpedo boat, and the latter would be sunk by it were not
all apertures closed so as to make her a true buoy. What appears
extraordinary is that the explosion does not prove as dangerous to the
assailant as to the adversary. To understand this it must be remembered
that, although the material with which the cartridges are filled is of
an extreme _shattering_ nature, and makes a breach in the most resistant
armor plate, when in _contact_ with it, yet, at a distance of a few
meters, no other effect is felt from it than the disturbance caused by
the water. This is why a space of 12 meters, represented by the length
of the torpedo spar, is sufficient to protect the torpedo boat. The
attack of an ironclad, however, under the conditions that we have just
described, is, nevertheless, a perilous operation, and one that requires
men of coolness, courage, and great experience.
[Illustration: ATTACK BY A TORPEDO BOAT UPON AN IRON CLAD SHIP OF WAR.]
There is another system which is likewise in use in the French navy, and
that is the Whitehead torpedo. This consists of a metallic cylinder,
tapering at each end, and containing not only a charge of gun cotton,
but a compressed air engine which actuates two helices. It is, in fact,
a small submarine vessel, which moves of itself in the direction toward
which it has been launched, and at a depth that has been regulated
beforehand by a special apparatus which is a secret with the inventor.
The torpedo is placed in a tube situated in the fore part of the torpedo
boat, and whence it is driven out by means of compressed air. Once
fired, it makes its way under the surface to the spot where the shock of
its point is to bring about an explosion, and the torpedo boat is thus
enabled to operate at a distance and avoid the dangers of an immediate
contact with the enemy. Unfortunately this advantage is offset by grave
drawbacks; for, in the first place, each of the Whitehead torpedoes
costs about ten thousand francs, without counting the expense of
obtaining the right to use the patent, and, in the second place, its
action is very uncertain, since currents very readily change its
direction. However this may be, the inventor has realized a considerable
sum by the sale of his secret to the different maritime powers, most of
whom have adopted his system.
All our ports are provided with flotillas and torpedo boats, and with
schools in which the officers and men charged with this service are
trained by frequent exercises. It was near L'Orient, at Port Louis, that
we were permitted to be witnesses of these maneuvers, and where we saw
the torpedo boats that were lying in ambush behind Rohellan Isle glide
between the rocks, all of which appeared familiar to them, and start out
seaward at the first signal. It was here, too, that we were witnesses
of the sham attack against a pleasure yacht, shown in one of our
engravings. A torpedo boat, driven at full speed, stopped at one meter
from the said yacht with a precision that denoted an oft-repeated study.
[Illustration: MODE OF FIRING TORPEDOES.]
Before we close, we must mention some very recent experiments that have
been made with a torpedo analogous to Whitehead's, that is to say, one
that runs alone by means of helices actuated by compressed air, but
having the great advantage that it can be steered at a distance from the
very place whence it has been launched. This extraordinary result is
obtained by the use of a rudder actuated by an electric current which is
transmitted by a small metallic cable wound up in the interior of the
torpedo, and paying out behind as the torpedo moves forward on its
mission. The operator, stationed at the starting point, is obliged to
follow the torpedo's course with his eyes in order to direct it during
its submarine voyage. For this reason the torpedo carries a vertical
mast, that projects above the surface, and at the top of which is placed
a lantern, whose light is thrown astern but is invisible from the front,
that is, from the direction of the enemy. A trial of this ingenious
invention was made a few weeks ago on the Bosphorus, with complete
success, as it appears. From the shore where the torpedo was put into
the water, the weapon was steered with sufficient accuracy to cause it
to pass, at a distance of two kilometers, between two vessels placed in
observation at a distance apart of ten meters. After this, it was made
to turn about so as to come back to its starting point. What makes this
result the more remarkable is that the waters of the Bosphorus are
disturbed by powerful currents that run in different directions,
according to the place.--_L'Illustration_.
* * * * *
PICTET'S HIGH SPEED BOAT.
It is now nearly a year ago since we announced to our readers the
researches that had been undertaken by the learned physicist, Raoul
Pictet, in order to demonstrate theoretically and practically the forms
that are required for a fast-sailing vessel, and since we pointed out
how great an interest is connected with the question, while at the same
time promising to revert to the subject at some opportune moment. We
shall now keep our promise by making known a work that Mr. Pictet has
just published in the _Archives Physiques et Naturelles_, of Geneva,
in which he gives the first results of his labors, and which we shall
analyze rapidly, neglecting in doing so the somewhat dry mathematical
part of the article.
For a given tonnage and identical tractive stresses, the greater or less
sharpness of the fore and aft part of the keel allows boats to attain
different speeds, the sharper lines corresponding to the highest speeds,
but, in practice, considerably diminishing the weight of freight capable
of being carried by the boat.
[Illustration: FIG. 1. PICTET'S HIGH SPEED BOAT.
A. Lateral View. B. Plan. C. Section of the boiler room. D. Section of
the cabin.]
Mr. Pictet proposed the problem to himself in a different manner, and as
follows:
Determine by analysis, and verify experimentally, what form of keel will
allow of the quickest and most economical carriage of a given weight of
merchandise on water.
We know that for a given transverse or midship section, the tractive
stress necessary for the progression of the ship is proportional to the
_square_ of the velocity; and the motive power, as a consequence, to the
_cube_ of such velocity.
[Illustration: Fig. 2.--Diagram of tractive stresses at different
speeds.]
The _friction_ of water against the polished surfaces of the vessel's
sides has not as yet been directly measured, but some indirect
experiments permit us to consider the resistances due thereto as small.
The entire power expended for the progress of the vessel is, then,
utilized solely in displacing certain masses of water and in giving them
a certain amount of acceleration. The masses of water set in motion
depend upon the surface submerged, and their acceleration depends upon
the speed of the vessel. Mr. Pictet has studied a form of vessel in
which the greatest part possible of the masses of water set in motion
shall be given a vertical acceleration, and the smallest part possible
a horizontal one; and this is the reason why: All those masses of water
which shall receive a vertical acceleration from the keel will tend to
move downward and produce a vertical reaction in an upward direction
applied to the very surface that gives rise to the motion. Such reaction
will have the effect of changing the level of the floating body; of
lifting it while relieving it of a weight exactly equal to the value
of the vertical thrust; and of diminishing the midship section, and,
consequently, the motive power.
[Illustration: Fig. 3.--Diagram of variations in tractive stresses and
tonnage taken as a function of the speed.]
All those masses of water which receive a horizontal acceleration from
the keel run counter, on the contrary, to the propulsive stress, and it
becomes of interest, therefore, to bring them to a minimum. The vertical
stress is limited by the weight of the boat, and, theoretically, with an
infinite degree of speed, the boat would graze the water without being
able to enter it.
The annexed diagram (Fig. 1) shows the form that calculation has led Mr.
Pictet to. The sides of the boat are two planes parallel with its axis,
and perfectly vertical. The keel (properly so called) is formed by
the joining of the two vertical planes. The surface thus formed is a
parabola whose apex is in front, the maximum ordinate behind, and the
concavity directed toward the bottom of the water. The stern is a
vertical plane intersecting at right angles the two lateral faces and
the parabolic curve, which thus terminates in a sharp edge. The prow of
the boat is connected with the apex of the parabola by a curve whose
concavity is directed upward.
[Illustration: Fig. 4.--Diagram of the variations in the power as a
function of the speed.]
When we trace the curve of the tractive stresses in a boat thus
constructed, by putting the speeds in abscisses and the tractive
stresses in ordinates, we obtain a curve (Fig. 2) which shows that the
same tractive stress applied to a boat may give it three different
speeds, M, M', and M'', only two of which, M and M'', are stable.
Experimental verifications of this study have been partially realized
(thanks to the financial aid of a number of persons who are interested
in the question) through the construction of a boat (Fig. 1) by the
Geneva Society for the Construction of Physical Instruments. The vessel
is 20.25 m. in length at the water line, has an everywhere equal width
of 3.9 m., and a length of 16 m. from the stern to the apex of the
parabola of the keel. The bottom of the boat is nearly absolutely flat.
The keel, which is 30 centimeters in width, contains the shaft of the
screw. The boiler, which is designed for running at twelve atmospheres,
furnishes steam to a two cylinder engine, which may be run at will,
either the two cylinders separately, or as a _compound_ engine. The
bronze screw is 1.3 m. in diameter, and has a pitch of 2.5 m. The vessel
has two rudders, one in front for slight speeds, and the other at the
stern. At rest, the total displacement is 52,300 kilogrammes.
This weight far exceeds what was first expected, by reason of the
superthickness given the iron plates of the vertical sides, of the
supplementary cross bracing, and of the superposition of the netting
necessary to resist the flexion of the whole. On another hand,
the tractive stress of the screw, which should reach about 4,000
kilogrammes, has never been able to exceed 1,800, because of the
numerous imperfections in the engine. It became necessary, therefore,
to steady the vessel by having her towed by the _Winkelried_, which was
chartered for such a purpose, to the General Navigation Company. It
became possible to thus carry on observations on speeds up to 27
kilometers per hour.
Fig. 3 shows how the tractive stress varies with each speed in a
theoretic case (dotted curve) in which the stress is proportional to the
square of the speed, in Madame Rothschild's boat, the _Gitana_ (curve
E), and in the Pictet high speed vessel (curve B).
The _Gitana_ was tried with speeds varying between 0 and 4 kilometers.
The corresponding tractive stresses have been reduced to the same
transverse section as in the Pictet model in order to render the
observations comparable. At slight speeds, and up to 19.5 kilometers per
hour, the _Gitana_, which is the sharper, runs easier and requires a
slighter tractive stress. At such a speed there is an equality; but,
beyond this, the Pictet boat presents the greater advantages, and, at a
speed of 27 kilometers, requires a stress about half less than does the
_Gitana_. Such results explain themselves when we reflect that at these
great speeds the _Gitana_ sinks to such a degree that the afterside
planks are at the level of the water, while the Pictet model rises
simultaneously fore and aft, thus considerably diminishing the submerged
section.
With low or moderate speeds there is a perceptible equality between the
theoretic curve and the curve of the fast boat; but, starting from 16
kilometers, the stress diminishes. The greater does the speed become,
the more considerable is the diminution in stress; and, starting from a
certain speed, the rise of the boat is such as to diminish its absolute
tractive stress--a fact of prime importance established by theory and
confirmed by experiment.
The curves in Fig. 4 show the power in horses necessary to effect
progression at different speeds. The curve, A, has reference to an
ordinary boat that preserves its water lines constant, and the curve,
B, to a swift boat of the same tonnage. Up to 16 kilometers, the swift
vessel presents no advantage; but beyond that speed, the advantage
becomes marked, and, at a speed of 27 kilometers, the power to be
expended is no more than half that which corresponds to the same speed
for an ordinary boat.
The water escapes in a thin and even sheet as soon as the tractive
stress exceeds 2,000 kilogrammes; and the intensity and size of
the eddies from the boat sensibly diminish in measure as the speed
increases.
The interesting experiments made by Mr. Pictet seem, then to clearly
establish the fact that the forms deduced by calculation are favorable
to high speeds, and will permit of realizing, in the future, important
saving in the power expended, and, consequently, in the fuel (much less
of which will need to be carried), in order to perform a given passage
within a given length of time. Thus is explained the great interest that
attaches to Mr. Pictet's labors, and the desire that we have to soon be
able to make known the results obtained with such great speeds, not when
the boat is towed, but when its propulsion is effected through its
own helix actuated by its own engine, which, up to the present,
unfortunately, has through its defects been powerless to furnish the
necessary amount of power for the purpose.--_La Nature_.
* * * * *
INITIAL STABILITY INDICATOR FOR SHIPS.
For a vessel with a given displacement, the metacenter and center of
gravity being known, it is easy to lay off in the form of a diagram
its stability or power of righting for any given angle of heel. Such a
diagram is shown in Fig. 3, in which the abscissae are the angles of the
heel, and the ordinates the various lengths of the levers, at the end
of which the whole weight of the vessel is acting to right itself.
The curve may be constructed in the following manner: Having found by
calculation the position of the transverse metacenter, M, for a given
displacement--Figs. 1 and 2--the metacentric height, G M, is then
determined either by calculations, or more correctly by experiment, by
varying the position of weights of known magnitude, or by the stability
indicator itself. Suppose, now, the vessel to be listed over to various
angles of heel--say 20 deg., 40 deg., 60 deg., and 80 deg.--the water
lines will then be A C, D E, F K, and H J respectively, and the centers
of buoyancy, which must be found by calculation, will be B1, B2, B3, and
B4. If lines are drawn from these points at right angles to the water
levels at the respective heels, the righting power of the vessel in each
position is found by taking the perpendicular distances between these
lines and the center of gravity, G. This method of construction is shown
to an enlarged scale in Fig. 2, where G is the center of gravity, B1
Z1, B2 Z2, B3 Z3, and B4 Z4 the lines from centers of buoyancy to water
levels; and G N, G O, and G P the distances showing the righting power
at the angles of 20 deg., 40 deg., and 60 deg. respectively, and which
to any convenient scale are set off as the ordinates in the stability
curve shown in Fig 3.
[Illustration: STABILITY INDICATOR FOR SHIPS. Fig. 1.]
Having obtained the curve, A, in this manner for a given metacentric
height, we will suppose that on the next voyage, with the same
displacement, it is found that, owing to some difference in stowage,
the center of gravity is 6 in. higher than before. The ordinates of the
curve will then be G N and G O--Fig.2--and the stability curve will
be as at C--Fig. 3--showing that at about 47 deg. all righting power
ceases. Similarly, if the center of gravity is lowered 6 in. on the
same displacement, the curve, B, will be found, and in this manner
comparative diagrams can be constructed giving at a glance the stability
of a vessel for any given draught of water and metacentric height.
[Illustration: STABILITY INDICATOR FOR SHIPS. Fig. 2.]
[Illustration: STABILITY INDICATOR FOR SHIPS. Fig. 3.]
The object of Mr. Alexander Taylor's indicator is to measure and show
by simple inspection the metacentric height under every condition of
loading, and therefore to make known the stability of the vessel. It
consists of a small reservoir, A, Fig. 4, placed at one side of the
ship, in the cabin, or other convenient locality, communicating by a
tube with the glass gauge, B, secured at the opposite side, the whole
being half filled with glycerine, which is the fluid recommended by Mr.
Wm. Denny, though water or any other liquid will answer the purpose.
At one side of the gauge is the circular scale, C, capable of being
revolved round its vertical axis, as well as adjusted up and down, so
as to bring the zero pointer exactly to the top of the fluid when the
vessel is without list. Round the top of the scale, at D, are engraved
four different draughts, and under these are the metacentric heights.
Test tanks of known capacity are placed at each side of the vessel, but
in no way connected with the reservoir or gauge. The metacentric height
is found as follows: The ship being freed from bilge water, the roller
scale is turned round to bring to the front the mark corresponding with
the mean draught of the vessel at the time, and the zero pointer is
placed opposite the surface of the liquid in the gauge. One of the test
tanks being filled with a known weight of water, the vessel is caused
to list, and in consequence the liquid in the tube takes a new position
corresponding with the degree of heel, the disturbance being greater
according as the vessel has been more or less overbalanced. The scale
having previously been properly graduated, the metacentric height for
the draught and state of loading can be at once read off in inches,
while as a check the water can be transferred from the one test tank to
the other, and the metacentric height read off as before, but on the
opposite side of the zero pointer. At the same time the angle of heel is
shown on a second graduated scale, E. Having obtained the metacentric
height, reference to a diagram will at once show the whole range of
stability; and this being ascertained at each loading, the stowage of
the cargo can be so adjusted as to avoid excessive stiffness in the one
hand and dangerous tenderness on the other. It will thus be seen that
Mr. Taylor's invention promises to be of great practical value both in
the hands of the ship-builder and ship-owner, who have now an instrument
placed before them, by the proper use of which all danger from
unskillful loading can be entirely avoided.--_The Engineer_.
[Illustration: STABILITY INDICATOR FOR SHIPS. Fig. 4.]
* * * * *
SCRIVANOW'S CHLORIDE OF SILVER PILE.
Considerable attention has been attracted lately at Paris among those
who are interested in electrical novelties to a chloride of silver
pile invented by Mr. Scrivanow. The experiments to which it has been
submitted are, in some respects, sufficiently extraordinary to cause us
to make them known to our readers, along with the inventor's description
of the apparatus.
Mr. Scrivanow's intention appears to be to apply this pile to the
lighting of apartments, and even to the running of small motors, and,
for the purpose of actuating sewing machines, he has already constructed
a small model whose external dimensions are 160 x 100 x 90 millimeters.
"My invention," says the inventor, "is intended as an electric pile
capable of regeneration. The annexed Fig. 1 shows a vertical arrangement
of the apparatus, and Fig. 2 a horizontal one. In the latter, two
elements are represented superposed.
"My pile consists of a prism of retort carbon (a) covered on every side
with pure chloride of silver (b). The carbon thus prepared is immersed
in a solution of hydrate of potassium (KHO) or of hydrate of sodium
(NaHO), marking 1.30 to 1.45 by the Baume areometer, the solvent being
water.
"In the vicinity of the carbon is arranged the plate to be attacked--a
plate of zinc (c) of good quality. The surface of the electrodes, and
their distance apart, depends upon the effects that it is desired to
obtain, and is determined in accordance with the well known principles
of electro-kinetics.
"The chemical reactions that take place in this couple are multiple.
In contact with a sufficiently concentrated solution of hydrate of
potassium or sodium, the chloride of silver, especially if it has been
recently prepared, passes partially into the state of brown or black
oxide, so that the carbon becomes covered, after remaining sufficiently
long in the exciting liquid, with a mixture of chloride and oxide of
silver. When the circuit is closed, the chloride becomes reduced to a
spongy metallic state and adheres to the surface of the carbon. At the
same time the zinc passes, in the alkaline solution, into a state of
chloride and of soluble combination of zinc oxide and of alkali.
"To avoid all loss of silver I cover the carbon with asbestos paper, or
with cloth of the same material, d. My piles are arranged in ebonite
vessels, A, which are flat, as in Fig. 1, or round, as in Fig. 2.
"In Fig 1 there is seen, at e, gutta-percha separating the zinc from the
carbon at the base.
"Under such conditions, we obtain a powerful couple that possesses an
electro-motive power of 1.5 to 1.8 volts, according to the concentration
of the exciting liquid. The internal resistance is extremely feeble. I
have obtained with piles arranged like those shown in the figures nearly
0.06 ohm, the measurements having been taken from a newly charged pile.
"When the element is used up, and, notably, when all the chloride of
silver is reduced, it is only necessary to plunge the carbon with its
asbestos covering (after washing it in water) into a chloridizing bath,
in order to bring back the metallic silver that invests the carbon to a
state of chloride, and thus restore the pile to its primitive energy.
After this the carbon is washed and put back into the exciting liquid.
"These reductions of the chloride of silver during the operation of the
pile can be reproduced _ad infinitum_, since they are accompanied by no
loss of metal. The alkaline liquid is sufficient in quantity for two
successive charges of the couple.
"The chloridizing bath consists of 100 parts of acetic acid, 5 to 6
parts, by weight, of hydrochloric acid, and about 30 parts of water.
[Illustration: FIG. 1.--SCRIVANOW'S CHLORIDE OF SILVER PILE.]
"Other acids may be employed equally as well. A bath composed of
chlorochromate of potassium and nitric or sulphuric acid makes an
excellent regenerator.
"To sum up, I claim as the distinctive characters of my pile:
"1. The use of the potassic or sodic alkaline liquid conjointly with
chloride of silver, and the oxide of the same, that forms through the
immersion of the carbon in a chloridizing bath.
"2. The use of retort or other carbon covered with the salt of silver
above specified.
"3. The arrangement and construction of my pile as I have described."
In the experiments recently tried with Mr. Scrivanow's pile, a large
sized battery was made use of, whose dimensions were 300 x 145 x 125
millimeters, and whose weight was from 5 to 6 kilogrammes. The results
were: intensity, 1 ampere; electro-motive power, 25 volts, corresponding
to an energy of 25 volt-amperes, or about 2.5 kilogrammeters per second.
The pile was covered with a copper jacket whose upper parts supported
two Swan lamps. Upon putting on the cover a contact was formed with the
electrodes, and it was possible by means of a commutator key with three
eccentrics to light or extinguish one of the lamps or both at once.
A single element would have sufficed to keep one Swan lamp of feeble
resistance lighted for 20 hours. Accepting the data given above and
the 20 hours' uninterrupted duration of the pile's operation the power
furnished by this large model is equal to 2.5 x 20 x 3,600 = 180,000
kilogrammeters.
[Illustration: FIG. 1.--SCRIVANOW'S CHLORIDE OF SILVER PILE.]
In our opinion, Mr. Scrivanow's pile is not adapted for industrial use
because of the expense of the silver and the frequent manipulations it
requires, but it has the advantage, however, of possessing, along with
its small size and little weight, a disposable energy of from 150,000
to 200,000 kilogrammeters utilizable at the will of the consumer and
securing to him a certain number of applications, either for lighting or
the production of power. It appears to us to be specially destined to
become a rival to the bichromate of potash pile for actuating electric
motors applied to the directing of balloons.--_Revue Industrielle_.
* * * * *
ON THE LUMINOSITY OF FLAME.
The light emitted from burning gases which burn with bright flame is
known to be a secondary phenomenon. It is the solid, or even liquid,
constituents separated out by the high temperature of combustion, and
rendered incandescent, that emit the light rays. Gases, on the other
hand, which produce no glowing solid or liquid particles during
combustion burn throughout with a weakly luminous flame of bluish or
other color, according to the kind of gas. Now, it is common to say,
merely, in explanation of this luminosity, that the gas highly heated in
combustion is self-incandescent. This explanation, however, has not been
experimentally confirmed. Dr Werner Siemens was, therefore, led recently
to investigate whether highly-heated pure gases really emit light.
The temperature employed in such experiments should, to be decisive,
be higher than those produced by luminous combustion. The author had
recourse to the regenerative furnace used by his brother, Friedrich, in
Dresden, in manufacture of hard glass. This stands in a separate room
which at night can be made perfectly dark. The furnace has, in the
middle of its longer sides, two opposite apertures, allowing free vision
through. It can be easily heated to the melting temperature of steel,
which is between 1,500 deg. and 2,000 deg. C. Before the furnace apertures were
placed a series of smoke blackened screens with central openings, which
enabled one to look through without receiving, on the eye, rays from the
furnace walls. If, now, all air exchange was prevented in the furnace,
and all light excluded from the room, it was found that not the least
light came to the eye from the highly-heated air in the furnace. For
success of the experiment, it was necessary to avoid any combustion in
the furnace, and to wait until the furnace-air was as free from dust as
possible. Any flame in the furnace (even when it did not reach into the
line of sight), and the least quantity of dust in it, illuminated the
field of vision.
As a result of these experiments, Dr. Siemens considers that the view
hitherto held, that highly-heated gases are self-luminous, is not
correct. In the furnace were the products of the previous combustion
and atmospheric air: consequently oxygen, nitrogen, carbonic acid, and
aqueous vapor. If even one of these gases was self-luminous, the field
of vision must have been always illuminated. The weak light given by
the flame of burning gases that separate out no solid nor liquid
constituents cannot, therefore, be explained as a phenomenon of glow of
the gaseous products.
It appealed to the author probable, that heated gases did not, either,
emit heat rays; and he set himself to test this idea, experimenting, in
company with Herr Froehlich, in Dresden. They first convinced themselves
in this case that the light emission of pure heated gases sunk to zero,
even when the field of vision was not always quite dark, and it was
only possible to observe this a short time; but the repeatedly observed
perfect darkness of the field of vision was demonstrative. On the other
hand, experiments made with sensitive thermopiles, in order to settle
the question of emission of heat-rays from highly-heated gases, failed.
Afterward, however, Dr. Siemens was convinced, by a quite simple
experiment of a different kind, that his supposition was erroneous. An
ordinary lamp, with circular wick, and short glass cylinder, was wholly
screened with a board, and a thermopile was so placed that its axis lay
somewhat higher than the edge of the board. As the room-walls had pretty
much a uniform temperature, the deflection of the galvanometer was but
slight, when the tube-axis of the thermopile was directed anywhere
outside of the hot-air current rising from the flame. When, however, the
axis was directed to this current, a deflection occurred, which was as
great as that from the luminous flame itself. That the heat radiation
from hot gases is but very small in comparison with that from equally
hot solid bodies, was shown by the large deflection produced when a
piece of fine wire was held in the hot-air current. On the other hand,
however, it was far too considerable to admit of being attributed to
dust particles suspended in the air current.
It must be conceded to be possible (the author says) that the light
radiation of hot gases, as also the heat radiation, is only exceedingly
weak, and therefore may escape observation. It is, therefore, much to
be desired that the experiments should be repeated at still higher
temperatures and with more exact instruments, in order to determine
the limit of temperature at which heated gases undoubtedly become
self-incandescent. The fact, however, that gases, at a temperature of
more than 1,500 deg. C, are not yet luminous, proves that the incandescence
of the flame is not to be explained as a self-incandescence of the
products of combustion. This is confirmed by the circumstance that, with
rapid mixture of the burning gases, the flame becomes shorter because
the combustion process goes on more quickly, and hotter because less
cold air has access. Further, the flame also becomes shorter and hotter
if the gases are strongly heated previous to combustion. As the rising
products of combustion still retain for a time the temperature of the
flame, the reverse must occur if the gases were self-luminous. The
luminosity of the flame, however, ceases at a sharp line of demarkation,
and evidently coincides with completion of the chemical action. The
latter, itself, therefore, and not the heating of the combustion
products, which is due to it, must be the cause of the luminosity. If
we suppose that the gas-molecules are surrounded by an ether-envelope,
then, in chemical combination of two or several such molecules, there
must occur a changed position of the ether-envelopes. The motion of
ether-particles thus caused may be represented by vibrations, which form
the starting-point of light and heat-waves.
In quite a similar manner we may also, according to Dr. Siemens,
represent the light-phenomenon occurring when an electric current
is sent through gases, which always takes place when the maximum of
polarization belonging to them is exceeded. As the passage of the
current through the gas seems to be always connected with chemical
action, the phenomenon of glow may be explained in the same way as in
flame, by oscillating transposition of the ether envelopes, by which the
passage of electricity is effected. In that case the light of flame may
be called electric light by the same light as the light of the ozone
tube or the Geissler tube, which is mainly to be distinguished from the
former in that it contains a dielectric of an extremely small maximum of
polarization. This correspondence in the causes of luminosity of flame,
and of gases traversed by electric currents, is supported by the
similarity of the flame-phenomena in strength and color of light.
[These researches were lately described by Dr. Werner Siemens to the
Berlin Academy.]
* * * * *
A QUICK WAY TO ASCERTAIN THE FOCUS OF A LENS.
It is well known that if the size of an object be ascertained, the
distance of a lens from that object, and the size of the image depicted
in a camera by that lens, a very simple calculation will give the
focus of the lens. In compound lenses the matter is complicated by the
relative foci of its constituents and their distance apart; but these
items, in an ordinary photographic objective, would so slightly affect
the result that for all practical purposes they may be ignored.
What we propose to do--what we have indeed done--is to make two of these
terms constant in connection with a diagram, here given, so that a mere
inspection may indicate, with its aid, the focus of a lens. All that is
required in making use of it is to plant the camera perfectly upright,
and place in front of it, at exactly fifteen feet from the center of the
lens, a two foot rule, also perfectly upright and with its center
the same height from the floor as the lens, and then, after focusing
accurately with as large a diaphragm as will give sharpness, to note the
size of the image and refer it to the diagram. The focus of the lens
employed will be marked under the line corresponding to the size of the
image of the rule on the ground glass.
As our object is to minimize time and trouble to the utmost, we may make
a suggestion or two as to carrying out the measuring. It will be obvious
that any object exactly two feet in length, rightly placed, will answer
quite as well as a "two-foot," which we selected as being about as
common a standard of length and as likely to be handy for use as
any. The pattern in a wall paper, a mark in a brick wall, a studio
background, or a couple of drawing pins pressed into a door, so long as
two feet exactly are indicated, will answer equally well.
And, further, as to the actual mode of measuring the image on the
ground glass (we may say that there is not the slightest need to take
a negative), it will perhaps be found the readiest method to turn the
glass the ground side outward, when two pencil marks may be made with
complete accuracy to register the length of the image, which can then be
compared with the diagram. Whatever plan is adopted, if the distance be
measured exactly between lens and rule, the result will give the focus
with exactitude sufficient for any practical purpose.--_Br. Jour. of
Photo_.
[Illustration]
* * * * *
THE HISTORY OF THE PIANOFORTE.
[Footnote: A paper recently read before the Society of Arts, London.]
By A. J. HIPKINS.
As this paper is composed from a technical point of view, some
elucidation of facts, forming the basis of it, is desirable before we
proceed to the chronological statement of the subject. These facts are
the strings, and their strain or tension; the sound-board, which is the
resonance factor; and the bridge, connecting it with the strings. The
strings, sound-board, and bridge are indispensable, and common to
all stringed instruments. The special fact appertaining to keyboard
instruments is the mechanical action interposed between the player and
the instrument itself. The strings, owing to the slender surface they
present to the air, are, however powerfully excited, scarcely audible.
To make them sufficiently audible, their pulsations have to be
communicated to a wider elastic surface, the sound-board, which, by
accumulated energy and broader contact with the air, re-enforces the
strings' feeble sound. The properties of a string set in periodic
vibration are the best known of the phenomena appertaining to acoustics.
The molecules composing the string are disturbed in the string's
vibrating length by the means used to excite the sound, and run off into
sections, the comparative length and number of which depend partly upon
the place in the string the excitement starts from; partly upon the
force and the form of force that is employed; and partly upon the
length, thickness, weight, strain, and elasticity of the string, with
some small allowance for gravitation. The vibrating sections are of
wave-like contour; the nodes or points of apparent rest being really
knots of the greatest pressure from crossing streams of molecules. Where
the pressure slackens, the sections rise into loops, the curves of which
show the points of least pressure. Now, if the string be struck upon a
loop, less energy is communicated to the string, and the carrying power
of the sound proportionately fails. If the string be struck upon a node,
greater energy ensues, and the carrying power proportionately gains.
By this we recognize the importance of the place of contact, or
striking-place of the hammer against the string; and the necessity, in
order to obtain good fundamental tone, which shall carry, of the note
being started from a node.
If the hammer is hard, and impelled with force, the string breaks into
shorter sections, and the discordant upper partials of the string, thus
brought into prominence, make the tone harsh. If the hammer is soft, and
the force employed is moderated, the harmonious partials of the longer
sections strike the ear, and the tone is full and round. By the
frequency of vibration, that is to say, the number of times a string
runs through its complete changes one way and the other, say, for
measurement, in a second of time, we determine the pitch, or relative
acuteness of the tone as distinguished by the ear.
We know, with less exactness, that the sound-board follows similar laws.
The formation of nodes is helped by the barring of the sound-board,
a ribbing crosswise to the grain of the wood, which promotes the
elasticity, and has been called the "soul" of stringed musical
instruments. The sound-board itself is made of most carefully chosen
pine; in Europe of the _Abies excelsa_, the spruce fir, which, when well
grown, and of light, even grain, is the best of all woods for resonance.
The pulsations of the strings are communicated to the sound-board by the
bridge, a thick rail of close-grained beech, curved so as to determine
their vibrating lengths, and attached to the sound-board by dowels. The
bridge is doubly pinned, so as to cut off the vibration at the edge
of the bearing the strings exert upon the bridge. The shock of each
separate pulsation, in its complex form, is received by the bridge,
and communicated to such undamped strings as may, by their lengths, be
sensitive to them; thus producing the AEolian tone commonly known as
sympathetic, an eminently attractive charm in the tone of a pianoforte.
We have here strings, bridge, and sound-board, or belly, as it is
technically called, indispensable for the production of the tone, and
indivisible in the general effect. The proportionate weight of
stringing has to be met by a proportionate thickness and barring of the
sound-board, and a proportionate thickness and elevation of the bridge.
The tension of the strings is met by a framing, which has become more
rigid as the drawing power of the strings has been gradually increased.
In the present concert grands of Messrs. Broadwood, that drawing power
may be stated as starting from 150 lb. for each single string in the
treble, and gradually increasing to about 300 lb. for each of the single
strings in the bass. I will reserve for the historical description of
my subject some notice of the different kinds of framing that have been
introduced. It will suffice, at this stage, to say that it was at first
of wood, and became, by degrees, of wood and iron; in the present day
the iron very much preponderating. It will be at once evident that the
object of the framing is to keep the ends of the strings apart. The near
ends are wound round the wrest-pins, which are inserted in the wooden
bed, called the wrest-plank, the strength and efficiency of which are
most important for the tone and durability of the instrument. It is
composed of layers of wainscot oak and beech, the direction of the
grain being alternately longitudinal and lateral. Some makers cover the
wrest-plank with a plate of brass; in Broadwood's grands, it is a plate
of iron, into which, as well as the wood, the wrest-pins are screwed.
The tuner's business is to regulate the tension, by turning the
wrest-pins, in which he is chiefly guided by the beats which become
audible from differing numbers of vibrations. The wrest-plank is
bridged, and has its bearing like the soundboard; but the wrest-plank
has no vibrations to transfer, and should, as far as possible, offer
perfect insensibility to them.
I will close this introductory explanation with two remarks, made by the
distinguished musician, mechanician, and inventor, Theobald Boehm, of
Munich, whose inventions were not limited to the flute which bears his
name, but include the initiation of an important change in the modern
pianoforte, as made in America and Germany. Of priority of invention he
says, in a letter to an English friend, "If it were desirable to analyze
all the inventions which have been brought forward, we should find that
in scarcely any instance were they the offspring of the brain of a
single individual, but that all progress is gradual only; each worker
follows in the track of his predecessor, and eventually, perhaps,
advances a step beyond him." And concerning the relative value of
inventions in musical instruments, it appears, from an essay of his
which has been recently published, that he considers improvement in
acoustical proportions the chief foundation of the higher or lower
degree of perfection in all instruments, their mechanism being but of
secondary value.
I will now proceed to recount briefly the history of the pianoforte from
the earliest mention of that name, continuing it to our contemporary
instruments, as far as they can be said to have entered into the
historical domain. It has been my privilege to assist in proving that
Bartolommeo Cristofori was, in the first years of the 18th century,
the real inventor of the pianoforte, but with a wide knowledge and
experience of how long it has taken to make any invention in keyed
instruments practicable and successful, I cannot believe that Cristofori
was the first to attempt to contrive one. I should rather accept his
good and complete instrument as the sum of his own lifelong studies and
experiments, added to those of generations before him, which have left
no record for us as yet discovered.
The earliest mention of the name pianoforte (_piano e forte_), applied
to a musical instrument, has been recently discovered by Count Valdrighi
in documents preserved in the Estense Library, at Modena. It is dated
A.D. 1598, and the reference is evidently to an instrument of the spinet
or cembalo kind; but how the tone was produced there is no statement,
no word to base an inference upon. The name has not been met with
again between the Estense document and Scipione Maffei's well-known
description, written in 1711, of Cristofori's "gravecembalo col piano e
forte." My view of Cristofori's invention allows me to think that the
Estense "piano e forte" may have been a hammer cembalo, a very imperfect
one, of course. But I admit that the opposite view of forte and piano,
contrived by registers of spinet-jacks, is equally tenable.
Bartolommeo Cristofori was a Paduan harpsichord maker, who was invited
by Prince Ferdinand dei Medici to Florence, to take charge of the large
collection of musical instruments the Prince possessed. At Florence he
produced the invention of the pianoforte, in which he was assisted and
encouraged by this high-minded, richly-cultivated, and very musical
prince. Scipione Maffei tells us that in 1709 Cristofori had completed
four of the new instruments, three of them being of the usual
harpsichord form, and one of another form, which he leaves undescribed.
It is interesting to suppose that Handel may have tried one or more of
these four instruments during the stay he made at Florence in 1708. But
it is not likely that he was at all impressed with the potentialities of
the invention any more than John Sebastian Bach was in after years when
he tried the pianofortes of Silbermann.
The sketch of Cristofori's action in Maffei's essay, from which I have
had a working model accurately made, shows that in the first instruments
the action was not complete, and it may not have been perfected when
Prince Ferdinand died in 1713. But there are Cristofori grand pianos
preserved at Florence, dated respectively 1720 and 1726, in which an
improved construction of action is found, and of this I also exhibit
a model. There is much difference between the two. In the second,
Cristofori had obtained his escapement with an undivided key,
reconciling his depth of touch, or keyfall, with that of the
contemporary harpsichord, by driving the escapement lever through the
key. He had contrived means for regulating the escapement distance, and
had also invented the last essential of a good pianoforte action, the
check. I will explain what is meant by escapement and check. When, by
a key being put down, the hammer is impelled toward the strings, it is
necessary for their sustained vibration that, after impact, the hammer
should rebound or escape; or it would, as pianoforte makers say,
"block," damping the strings at the moment they should sound.
A dulcimer player gains his elastic blow by the free movement of the
wrist. To gain a similarly elastic blow mechanically in his first
action, Cristofori cut a notch in the butt of his hammer from which the
escapement lever, "linguetta mobile" as he called it--"hopper," as we
call it--being centered at the base, moved forward, when the key was put
down, to the extent of its radius, and after the delivery of the blow
returned to its resting place by the pressure of a spring. The first
action gave the blow with more direct force than the second, which had
the notch upon what is called the underhammer, but was defective in
the absence of any means to regulate the distance of the "go-off," or
"escapement" from the string. In the second action, a small check before
the hopper is intended to regulate it, but does so imperfectly. The
pianoforte had to wait for fifty years for satisfactory regulation of
the escapement.
In the first action, the hammer rests in a silken fork, dropping the
whole distance of the rise of every blow. The check in the second
action, the "paramartello," is next in importance to the escapement. It
catches the back part of the hammer at different points of the radius,
responding to the amount of force the player has used upon the key. So
that in repeated blows, the rise of the hammer is modified, and the
notch is nearer to the returning hopper in proportionate degree.
I have given the first place in description to Cristofori's actions,
instead of to the "cembalo" or instrument to which they were applied,
because piano and forte, from touch, became possible through them, and
what else was accomplished by Cristofori was due, primarily, to the
dynamic idea. He strengthened his harpsichord sound-board against
a thicker stringing, renouncing the cherished sound-holes. Yet the
sound-box notion clung to him, for he made openings in his sound-board
rail for air to escape. He ran a string-block round the case, entirely
independent of the sound-board, and his wrest-plank, which also became
a separate structure, removed from the sound-board by the gap for the
hammers, was now a stout oaken plank which, to gain an upward bearing
for the strings, he inverted, driving his wrest-pins through in the
manner of a harp, and turning them in like fashion to the harp. He had
two strings to a note, but it did not occur to him to space them into
pairs of unisons. He retained the equidistant harpsichord scale, and
had, at first, under-dampers, later over-dampers, which fell between the
unisons thus equally separated. Cristofori died in 1731. He had pupils,
one of whom made, in 1730, the, "Rafael d'Urbino," the favorite
instrument of the great singer Farinelli. The story of inventive
Italian pianoforte making ends thus early, but to Italy the invention
indisputably belongs.
The first to make pianofortes in Germany was the famous Freiberg
organ-builder and clavichord maker, Gottfried Silbermann. He submitted
two pianofortes to the judgment of John Sebastian Bach in 1726, which
judgment was, however, unfavorable; the trebles being found too weak,
and the touch too heavy. Silbermann, according to the account of Bach's
pupil, Agricola, being much mortified, put them aside, resolving not to
show them again unless he could improve them. We do not know what these
instruments were, but it may be inferred that they were copies of
Cristofori, or were made after the description of his invention by
Maffei, which had already been translated from Italian into German,
by Koenig, the court poet at Dresden, who was a personal friend of
Silbermann. With the next anecdote, which narrates the purchase of all
the pianofortes Silbermann had made, by Frederick the Great, we are upon
surer ground. This well accredited occurrence took place in 1746. In
the following year occurred Bach's celebrated visit to Potsdam, when he
played upon one or more of these instruments. Burney saw and described
one in 1772. I had this one, which was known to have remained in the new
palace at Potsdam until the present time unaltered, examined, and, by a
drawing of the action, found it was identical with Cristofori's. Not,
however, being satisfied with one example, I resolved to go myself to
Potsdam; and, being furnished with permission from H.R.H. the Crown
Princess of Prussia, I was enabled in September, 1881, to set the
question at rest of how many grand pianofortes by Gottfried Silbermann
there were still in existence at Potsdam, and what they were like. At
Berlin there are none, but at Potsdam, in the music-rooms of Frederick
the Great, which are in the town palace, the new palace, and Sans
Souci--left, it is understood, from the time of Frederick's death
undisturbed--there are three of these Silbermann pianofortes. All three
are with unimportant differences having nothing to do with structure,
Cristofori instruments, wrest plank, sound-board, string-block, and
action; the harpsichord scale of stringing being still retained. The
work in them is undoubtedly good; the sound-boards have given in the
trebles, as is usual with old instruments, from the strain; but I should
say all three might be satisfactorily restored. Some other pianofortes
seem to have been made in North Germany about this time, as our own
poet Gray bought one in Hamburg in 1755, in the description of which we
notice the desire to combine a hammer action with the harpsichord which
so long exercised men's minds.
The Seven Years' War put an end to pianoforte making on the lines
Silbermann had adopted in Saxony. A fresh start had to be made a few
years later, and it took place contemporaneously in South Germany and
England. The results have been so important that the grand pianofortes
of the Augsburg Stein and the London Backers may be regarded,
practically, as reinventions of the instrument. The decade 1770-80 marks
the emancipation of the pianoforte from the harpsichord, of which before
it had only been deemed a variety. Compositions appear written expressly
for it, and a man of genius, Muzio Clementi, who subsequently became the
head of the pianoforte business now conducted by Messrs. Collard, came
forward to indicate the special character of the instrument, and found
an independent technique for it.
A few years before, the familiar domestic square piano had been
invented. I do not think clavichords could have been altered to square
pianos, as they were wanting in sufficient depth of case; but that the
suggestion was from the clavichord is certain, the same kind of case and
key-board being used. German authorities attribute the invention to an
organ builder, Friederici of Gera, and give the date about 1758 or 1760.
I have advertised in public papers, and have had personal inquiry made
for one of Friederici's "Fort Biens," as he is said to have called his
instrument. I have only succeeded in learning this much--that Friederici
is considered to have been of later date than has been asserted in the
text-books. Until more conclusive information can be obtained, I must
be permitted to regard a London maker, but a German by birth, Johannes
Zumpe, as the inventor of the instrument. It is certain that he
introduced that model of square piano which speedily became the fashion,
and was chosen for general adoption everywhere. Zumpe began to make
his instruments about 1765. His little square, at first of nearly five
octaves, with the "old man's head" to raise the hammer, and "mopstick"
damper, was in great vogue, with but little alteration, for forty years;
and that in spite of the manifest improvements of John Broadwood's
wrest-plank and John Geib's "grasshopper." After the beginning of this
century, the square piano became much enlarged and improved by Collard
and Broadwood, in London, and by Petzold, in Paris. It was overdone in
the attempt to gain undue power for it, and, about twenty years ago,
sank in the competition, with the later cottage pianoforte, which was
always being improved.
To return to the grand pianoforte. The origin of the Viennese grand is
rightly accredited to Stein, the organ builder, of Augsburg. I will
call it the German grand, for I find it was as early made in Berlin as
Vienna. According to Mozart's correspondence, Stein had made some grand
pianos in 1777, with a special escapement, which did not "block"
like the pianos he had played upon before. When I wrote the article
"Pianoforte" in Dr. Grove's "Dictionary," no Stein instrument was
forthcoming, but the result of the inquiries I had instituted at that
time ultimately brought one forward, which has been secured by the
curator of the Brussels Museum, M. Victor Mahillon. This instrument,
with Stein's action and two unison scale, is dated 1780. Mozart's grand
piano, preserved at Salzburg, made by Walther, is a nearly contemporary
copy of Stein, and so also are the grands by Huhn, of Berlin, which I
took notes of at Berlin and Potsdam; the latest of these is dated 1790.
An advance shown by these instruments of Stein and Stein's followers is
in the spacing of the unisons; the Huhn grands having two strings to
a note in the lower part of the scale, and three in the upper. The
Cristofori Silbermann inverted wrest-plank has reverted to the usual
form; the tuning pins and downward bearing being the same as in the
harpsichord. There are no steel arches as yet between the wrest-plank
and the belly-rail in these German instruments. As to Stein's
escapement, his hopper was fixed behind the key; the axis of the hammer
rising on a principle which I think is older than Stein, but have not
been able to trace to its source, and the position of his hammer is
reversed. Stein's light and facile movement with shallow key-fall,
resembling Cristofori's in bearing little weight, was gratefully
accepted by the German clavichord players, and, reacting, became one of
the determining agents of the piano music and style of playing of the
Vienna school. Thus arose a fluent execution of a rich figuration and
brilliant passage playing, with but little inclination to sonorousness
of effect, lasting from the time of Mozart's immediate followers to that
of Henri Herz; a period of half a century. Knee-pedals, as we translate
"geuouilleres," were probably in vogue before Stein, and were levers
pressed with the knees, to raise the dampers, and leave the pianoforte
undamped, a register approved of by Carl Philip Emmanuel Bach, who
regarded the undamped pianoforte as the more agreeable for improvising..
He appears, however, to have known but little of the capabilities of
the instrument, which seemed to him coarse and inexpressive beside his
favorite clavichord. Stein appears to have made use of the "una corda"
shift. Probably by knee-pedals, subsequently by foot-pedals, the
following effects were added to the Stein pianos.
The harpsichord "harp"-stop, which muted one string of each note by
a piece of leather, became, by the interposition of a piece of cloth
between the hammer and the strings, the piano, harp, or _celeste_. The
more complete sourdine, which muted all the strings by contact of a long
strip of leather, acted as the staccato, pizzicato, or pianissimo. The
Germans further displayed that ingenuity in fancy stops Mersenne had
attributed to them in harpsichords more than a hundred and fifty years
before, by a bassoon pedal, a card which by a rotatory half-cylinder
just impinging upon the strings produced a reedy twang; also by pedals
for triangle, cymbals, bells, and tambourine, the last drumming on the
sound-board itself.
Several of these contrivances may be seen in a six-pedal grand
pianoforte belonging to Her Majesty the Queen, at Windsor Castle,
bearing the name as maker of Stein's daughter, Nannette, who was a
friend of Beethoven. The diagram represents the wooden framing of such
an instrument.
We gather from Burney's contributions to "Rees's Cyclopaedia," that
after the arrival of John Christian Bach in London, A.D. 1759, a few
grand pianofortes were attempted, by the second-rate harpsichord makers,
but with no particular success. If the workshop tradition can be relied
upon that several of Silbermann's workmen had come to London about that
time, the so-called "twelve apostles," more than likely owing to the
Seven Years' War, we should have here men acquainted with the Cristofori
model, which Silbermann had taken up, and the early grand pianos
referred to by Burney would be on that model. I should say the "new
instrument" of Messrs. Broadwood's play-bill of 1767 was such a grand
piano; but there is small chance of ever finding one now, and if an
instrument were found, it would hardly retain the original action, as
Messrs. Broadwood's books of the last century show the practice of
refinishing instruments which had been made with the "old movement."
[Illustration: Fig. 1.]
Burney distinguishes Americus Backers by special mention. He is said
to have been a Dutchman. Between 1772 and 1776, Backers produced the
well-known English action, which has remained the most durable and one
of the best up to the present day. It refers in direct leverage to
Cristofori's first action. It is opposite to Stein's contemporary
invention, which has the hopper fixed. In the English action, as in the
Florentine, the hopper rises with the key. To the direct leverage of
Cristofori's first action, Backers combined the check of the second, and
then added an important invention of his own, a regulating screw and
button for the escapement. Backers died in 1776. It is unfortunate we
can refer to no pianoforte made by him. I should regard it as treasure
trove if one were forthcoming in the same way that brought to light the
authentic one of Stein's. As, however, Backers' intimate friends, and
his assistants in carrying out the invention, were John Broadwood and
Robert Stodart, we have, in their early instruments, the principle and
all the leading features of the Backers grand. The increased weight
of stringing was met by steel arches placed at intervals between the
wrest-plank and the belly-rail, but the belly-rail was still free from
the thrust of the wooden bracing, the direction of which was confined to
the sides of the case, as it had been in the harpsichord.
Stodart appears to have preceded Broadwood in taking up the manufacture
of the grand piano by four or five years. In 1777 he patented an
alternate pianoforte and harpsichord, the drawing of which patent shows
the Backers action. The pedals he employed were to shift the harpsichord
register and to bring on the octave stop. The present pedals were
introduced in English and grand pianos by 1785, and are attributed to
John Broadwood, who appears to have given his attention at once to the
improvement of Backers' instrument. Hitherto the grand piano had been
made with an undivided belly-bridge, the same as the harpsichord had
been; the bass strings in three unisons, to the lowest note, being of
brass. Theory would require that the notes of different octaves should
be multiples of each other and that the tension should be the same for
each string. The lowest bass strings, which at that time were the note
F, would thus require a vibrating length of about twelve feet. As only
half this length could be afforded, the difference had to be made up in
the weight of the strings and their tension, which led, in these early
grands, to many inequalities. The three octaves toward the treble could,
with care, be adjusted, the lengths being practically the ideal lengths.
It was in the bass octaves (pianos were then of five octaves) the
inequalities were more conspicuous. To make a more perfect scale and
equalize the tension was the merit and achievement of John Broadwood,
who joined to his own practical knowledge and sound intuitions the aid
of professed men of science. The result was the divided bridge, the bass
strings being carried over the shorter division, and the most beautiful
grand pianoforte in its lines and curves that has ever been made was
then manufactured. In 1791 he carried his scale up to C, five and a
half octaves; in 1794 down to C, six octaves, always with care for the
artistic, form. The pedals were attached to the front legs of the stand
on which the instrument rested. The right foot-pedal acted first as
the piano register, shifting the impact of each hammer to two unisons
instead of three; a wooden stop in the right hand key-block permitted
the action to be shifted yet further to the right, and reducing the blow
to one string only, produced the pianissimo register or _una corda_ of
indescribable attractiveness of sound. The cause of this was in the
reflected vibration through the bridge to the untouched strings. The
present school of pianoforte playing rejects this effect altogether, but
Beethoven valued it, and indicated its use in some of his great works.
Steibert called the _una corda_ the _celeste_, which is more appropriate
to it than Adam's application of this name to the harp-stop, by which
the latter has gone ever since.
Up to quite the end of the last century the dampers were continued to
the highest note in the treble. They were like harpsichord dampers
raised by wooden jacks, with a rail or stretcher to regulate their rise,
which served also as a back touch to the keys. I have not discovered the
exact year when, or by whom, the treble dampers were first omitted,
thus leaving that part of the scale undamped. This bold act gave the
instrument many sympathetic strings free to vibrate from the bridge when
the rest of the instrument was played, each string, according to its
length, being an aliquot division of a lower string. This gave the
instrument a certain brightness or life throughout, an advantage which
has secured its universal adoption. The expedients of an untouched
octave string and of utilizing those lengths of wire that lie beyond the
bridges have been brought into notice of late years, but the latter was
early in the century essayed by W. F. Collard.
From difficulties of tuning, owing to friction and other causes, the
real gain of these expedients is small, and when we compare them with
the natural resources we have always at command in the normal scale
of the instrument, is not worth the cost. The inventor of the damper
register opened a floodgate to such aliquot re-enforcement as can be got
in no other way. Each lower note struck of the undamped instrument,
by excitement from the sound-board carried through the bridge, sets
vibrating higher strings, which, by measurement, are primes to its
partials; and each higher string struck calls out equivalent partials
in the lower strings. Even partials above the primes will excite
their equivalents up to the twelfth and double octave. What a glow of
tone-color there is in all this harmonic re-enforcement, and who would
now say that the pedals should never be used? By their proper use,
the student's ear is educated to a refined sense of distinction of
consonance and dissonance, and the intention and beauty of Chopin's
pedal work becomes revealed.
The next decade, 1790-1800, brings us to French grand pianoforte-making,
which was then taken up by Sebastian Erard. This ingenious mechanic and
inventor traveled the long and dreary road along which nearly all who
have tried to improve the pianoforte have had to journey. He appears, at
first, to have adopted the existing model of the English instrument in
resonance, tension, and action, and to have subsequently turned his
attention to the action, most likely with the idea of combining the
English power of gradation with the German lightness of touch. Erard
claimed, in the specification to a patent for an action, dated 1808,
"the power of giving repeated strokes, without missing or failure, by
very small angular motions of the key itself."
Once fairly started, the notion of repetition became the dominant idea
with pianoforte-makers, and to this day, although less insisted upon,
engrosses time and attention that might be more usefully directed. Some
great players, from their point of view of touch, have been downright
opposed to repetition actions. I will name Kalkbrenner, Chopin, and, in
our own day, Dr. Hans von Buelow. Yet the Erard's repetition, in the form
of Hertz's reduction, is at present in greater favor in America and
Germany, and is more extensively used, than at any previous period.
The good qualities of Erard's action, completed in 1821, the germ of
which will be found in the later Cristofori, are not, however, due to
repetition capability, but to other causes, chiefly, I will say, to
counterpoise. The radical defect of repetition is that the repeated
note can never have the tone-value of the first; it depends upon the
mechanical contrivance, rather than the finder of the player, which is
directly indispensable to the production of satisfactory tone. When the
sensibility of the player's touch is lost in the mechanical action, the
corresponding sensibility of the tone suffers; the resonance is not,
somehow or other, sympathetically excited.
Erard rediscovered an upward bearing, which had been accomplished by
Cristofori a hundred years before, in 1808. A down-bearing bridge to the
wrest-plank, with hammers striking upward, are clearly not in relation;
the tendency of the hammer must be, if there is much force used, to
lift the string from its bearing, to the detriment of the tone. Erard
reversed the direction of the bearing of the front bridge, substituting
for a long, pinned, wooden bridge, as many little brass bridges as there
were notes. The strings passing through holes bored through the little
bridges, called agraffes, or studs, turned upward toward the wrest-pin.
By this the string was forced against its rest instead of off it. It
is obvious that the merit of this invention would in time make its use
general. A variety of it was the long brass bridge, specially used
in the treble on account of the pleasant musical-box like tone its
vibration encouraged. Of late years another upward bearing has found
favor in America and on the Continent, the Capo d'Astro bar of M. Bord,
which exerts a pressure upon the strings at the bearing point.
About the year 1820, great changes and improvements were made in the
grand pianoforte both externally and in the instrument. The harpsichord
boxed up front gave way to the cylinder front, invented by Henry Pape,
a clever German pianoforte-maker who bad settled in Paris. Who put the
pedals upon the familiar lyre I have not been able to learn. It would
be in the Empire time, when a classical taste was predominant. But the
greatest change was from a wooden resisting structure to one in which
iron should play an important part. The invention belongs to this
country, and is due to a tuner named William Allen, a young Scotchman,
who was in Stodart's employ. With the assistance of the foreman, Thom,
the invention was completed, and a patent was taken out, dated the 15th
of January, 1820, in which Thom was a partner. The patent was, however,
at once secured by the Stodarts, their employers. The object of the
patent was a combination of metal tubes with metal plates, the metallic
tubes extending from the plates which were attached to the string-block
to the wrest-plank. The metal plates now held the hitch-pins, to which
the farther ends of the strings were fixed, and the force of the tension
was, in a great measure, thrown upon the tubes. The tubes were a
mistake; they were of iron over the steel strings, and brass over the
brass and spun strings, the idea being that of the compensation of
tuning when affected by atmospheric change, also a mistake. However,
the tubes were guaranteed by stout wooden bars crossing them at right
angles. At once a great advance was made in the possibility of using
heavier strings, and the great merit of the invention was everywhere
recognized.
James Broadwood was one of the first to see the importance of the
invention, if it were transformed into a stable principle. He had tried
iron tension bars in past years, but without success. It was now due to
his firm to introduce a fixed stringed plate, instead of plates intended
to shift, and in a few years to combine this plate with four solid
tension bars, for which combination he, in 1827, took out a patent,
claiming as the motive for the patent the string-plate; the manner of
fixing the hitch-pins upon it, the fourth tension bar, which crossed the
instrument about the middle of the scale, and the fastening of that bar
to the wooden brace below, now abutting against the belly-rail, the
attachment being effected by a bolt passing through a hole cut in the
sound-board.
This construction of grand pianoforte soon became generally adopted in
England and France. Messrs. Erard, who appear to have had their own
adaptation of tension bars, introduced the harmonic bar in 1838. This,
a short bar of gun metal, was placed upon the wrest-plank immediately
above the bearings of the treble, and consolidated the plank by screws
tapped into it of alternate pressure and drawing power. In the original
invention a third screw pressed upon the bridge. By this bar a very
light, ringing treble tone was gained. This was followed by a long
harmonic bar extending above the whole length of the wrest-plank, which
it defends from any tendency to rise, by downward pressure obtained by
screws. During 1840-50, as many as five and even six tension bars were
used in grand pianofortes, to meet the ever increasing strain of
thicker stringing. The bars were strutted against a metal edging to the
wrest-plank, while the ends were prolonged forward until they abutted
against its solid mass on the key-board side of the tuning-pins. The
space required for fixing them cramped the scale, while the strings were
divided into separate batches between them. It was also difficult to
so adjust each bar that it should bear its proportionate share of the
tension; an obvious cause of inequality.
Toward the end of this period a new direction was taken by Mr. Henry
Fowler Broadwood, by the introduction of an iron-framed pianoforte, in
which the bars should be reduced in number, and with the bars the steel
arches, as they were still called, although they were no longer arches
but struts.
In a grand pianoforte, made in 1847, Mr. Broadwood succeeded in
producing an instrument of the largest size, practically depending upon
iron alone. Two tension bars sufficed, neither of them breaking into the
scale: the first, nearly straight, being almost parallel with the lowest
bass string; the second, presenting the new feature of a diagonal bar
crossed from the bass corner to the string-plate, with its thrust at an
angle to the strings.
There were reasons which induced Mr. Broadwood to somewhat modify and
improve this framing, but with the retention of its leading feature, the
diagonal bar, which was found to be of supreme importance in bearing the
tension where it is most concentrated. From 1852, his concert grands
have had, in all, one bass bar, one diagonal bar, a middle bar with
arch beneath, and the treble cheek bar. The middle bar is the only one
directly crossing the scale, and breaking it. It is strengthened by
feathered ribs, and is fastened by screws to the wooden brace below. The
three bars and diagonal bar, which is also feathered, abut firmly on the
string plate, which is fastened down to the wooden framing by screws.
Since 1862, the wooden wrest-plank has been covered with a plate of
iron, the iron screw-pin plate bent at a right angle in front. The
wrest-pins are screwed into this plate, and again in the wood below.
The agraffes, which take the upward bearings of the strings, are firmly
screwed into this plate. The long harmonic bar of gun metal lies
immediately above the agraffes, and crossing the wrest-plank in its
entire width, serves to keep it, at the bearing line, in position. This
construction is the farthest advance of the English pianoforte.
[Illustration: FIG. 2.--WILLIAM ALLEN.]
Almost simultaneously with it has arisen a new development in America,
which, beginning with Conrad Meyer, about 1833, has been advanced by the
Chickerings and Steinways to the well known American and German grand
pianoforte of the present day. It was perfected in America about in
1859, and has been taken up since by the Germans almost universally, and
with very little alteration. Two distinct principles have been developed
and combined--the iron framing in a single casting, and the cross or
overstringing. I will deal with the last first, because it originated in
England and was the invention of Theobald Boehm, the famous improver of
the flute. In Grove's "Dictionary," I have given an approximate date to
his overstringing as 1835, but reference to Boehm's correspondence with
Mr. Walter Broadwood shows me that 1831 was really the time, and
that Boehm employed Gerock and Wolf, of 79 Cornhill, London, musical
instrument makers, to carry out his experiment. Gerock being opposed
to an oblique direction of the strings and hammers, Boehm found a more
willing coadjutor in Wolf. As far as I can learn, a piccolo, a cabinet,
and a square piano were thus made overstrung. Boehm's argument was that
a diagonal was longer within a square than a vertical, which, as he
said, every schoolboy knew. The first overstrung grand pianos seen in
London were made by Lichtenthal, of St. Petersburg; not so much for tone
as for symmetry of the case; two instruments so made were among the
curiosities of the Great Exhibition of 1851. Some years before this,
Henry Pape had made experiments in cross stringing, with the intention
to economize space. His ideas were adopted and continued by the London
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