Copyright
Richard Green Parker.

A school compendium of natural and experimental philosophy : embracing the elementary principles of mechanics, hydrostatics, hydraulics, pneumatics, acoustics, pyronomics, optics, electricity, galvanism, magnetism, electro-magnetism, magneto-electricity, astronomy : containing also a description of online

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Online LibraryRichard Green ParkerA school compendium of natural and experimental philosophy : embracing the elementary principles of mechanics, hydrostatics, hydraulics, pneumatics, acoustics, pyronomics, optics, electricity, galvanism, magnetism, electro-magnetism, magneto-electricity, astronomy : containing also a description of → online text (page 28 of 38)
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or near the poles, it is wound so as to form six thicknesses. Bo
ing connected with a battery consisting of plates, containing u
little less than forty-eight square feet of surface, the ipagnet
supported the prodigious weight stated above, namely, 2063
pounds.

1171. HE- Fig- 169.

Explain Fig. LIACAL RlNO>

Fig. 169 rep-
resents a heliacal ring, or ring
of wire bent in the form of a
helix, with the ends of the *
wire left free to be inserted
in the screw-cups of a bat-
tery. Two semicircular pieces
of soft unmagnetized iron,
furnished with rings, the
upper one for the hand, the
lower one for weights,
tire prepared to be inserted
into the helix, in the manner
of the links of a chain. As
soon as the ends of the helix
are inserted into the screw-
cups of the battery, the rings will be held together, with gre;;t
force, by magnetic attraction.

1172. That the attraction is caused, or that the magnetism is in-
duced, by the circulation of electricity around the coils, may be
proved by the following interesting experiment. Hold the heliacal
ring horizontally over a plate of small nails, and suspend an unmag-
netized bar perpendiculai ly on the outside of the ring, over the nails,
and there will be no attraction. Suspend the bar perpendicularly
through the helix, and the nails will all attach themselves to it in
the form of tangents to the circles formed by the coils of the helia
cal ring.

H ehors&- 1-173. Communication of Magnetism to Steel
shoe magnets by tfie Electro-magnet. Bars of the U fora?




ELECTKO-MAGNET1G TELEGKAPH .



most readily are most readily magnetized by drawing them
from the bend to the extremities, across the
poles of the U electro-magnet, in such a way that both halves
of the bar may pass at the same time over the poles to which
they are applied. This should be repeated several times, recol-
lecting always to draw the bar in the same direction.

1174. Fig. 170 represents the U electro-
magnet with the bar to be magnetized. Whec
the bar is thick, both surfaces should be drawn
across the electro-magnet, keeping each half applied to the
same pole. To remove the magnetism, it is only necessary to

Fig. 170.



Explain Fig.
1TO.




On what funda-
mental principle
is the Electric
Telegraph con-
constructed 1



reverse the process by which it was magnetized, that is, to draw
the bar across the electro-magnet in a contrary direction.

1175. THE ELECTRO-MAGNETIC TELEGRAPH.*
From the description which has now been
given of the electro-magnetic power, it will
readily be perceived that a great force can be
made to act simply by bringing a wire into
contact with another conductor, and that the force can be in-
stantly arrested in its operation by removing the wire from the
contact ; in other words, that by connecting and disconnecting
a helix with a battery, a prodigious power can be made succes

* The word telegraph is compounded of two Greek words, rtfts (tele), sig-
nifying at a distance, and ynayo (grapho), to write, that is, to signify or to
write at a distance. The word telescope is another compound of the word
fijit with the word ox^nia: (scrpio), to see, an instrument to see at a di*
tartce.



B"0 NATURAL PHILOS01 IIY

eively to act and cease to act. Advantage has been taktii o'
this principle in the construction of the American electro-mag;
netic telegraph, which was matured by Professor Morse, and
first put into operation between the cities of Baltimore and
. Washington, in 1844> It was not, however,

ies 'rendereTl-he unti * Professor Henry, of Princeton, New Jer-
magnetic tele- sey, had discovered the mode of constructing
tfraph possible? the power f ul electro-magnets which have been
noticed, that this form of the telegraph became possible.

1176. The principles of its construction may
Explain the man- b b { fl d fon ^.

ner m which the J

electric telegraph An electro-magnet is so arranged with its
performs its armature that when the armature is attracted

it communicates its motion to a lever, to which
a blunt point is attached, which marks a narrow strip of paper,
drawn under it by machinery resembling clock-work, whenever
the electro-magnet is in action. When the electro-magnet ceases
to act, the armature falls, arid, communicating its motion to the
lever, the blunt point is removed from its contact with the paper.
By this means, if one of the wires from the battery is attached
to the screw-cup, whenever the other wire is attached to the
remaining cup the armature is powerfully attracted by the
magnet, and the point on the lever presses the paper into the
groove, of a roller, thereby making an indentation on the paper,
corresponding in length to the time during which the contact
with the battery is maintained, the paper being drawn slowly
under the roller.

1177. In the construction of the electric tele-
\Vhat is the
agent in the graph the first object of consideration is the de-

electrti tele- yelopment of the agent. The agent is the electric

fluid, which is brought into action by a battery.
The forms of batteries chiefly employed for this purpose are
Grove's, Bunsen's, Daniel's, Snell's or its modifications, and Le-
clanche's. If the telegraph is in constant use, and the battery is
to be renewed at intervals of two or three days, one of the first
above mentioned is used.



EJ,KCTKO-MAGNETIO TELEGKAPH.



Fig. lYl represents a battery composed of
ffxplatn Fig. twe j ve Cll p s> on t ^ e p r i nc ip] e o f Grove's battery,

each cup containing a thick cylinder of zinc,
with a porous cell, two acids, and a strip of platinum, as
described in Fijr. 104. The chemical action of the acids on the



Fig. 171




Fig. 172.



zinc generates a powerful current of electricity towards the
screw-cups at A B.

1178. The second step in the construction of
Explain Fig. ^ telegraph is rep rescntcd by Fig. 172. The
wires from the battery represented in Fig. 171
are carried to the screw-cups in the apparatus represented by
Fig. 172, called the sig-
nal-key, A to A and B
to B, respectively. It
will be observed that the
cups of the signal-key are
insulated, and that the
electric fluid can finish its
circuit only when the fin-
ger depresses the knob
and makes it come in con-
tact with the metallic strip below, thus forming a communication
between the screw-cups. The signal -key thus regulates the com-
pletion of the circuit, and the flow of the current of electricity,
ut the will of the operator.




822



NA1UKAL PHILOSOPHY.



1179. The signal-key is made in several
Explain Fig. forms in the different telegraphs, and in Fig.

173 is represented in its more perfect construc-
tion. It coir Ists of a lever, mounted on a horizontal axis, with
a, knob of ivory for the hand at the extremity of the long arm.
wrhich is at the left in
the cut. This lever is
thrown up by a spring,
so as to avoid contact
with the button on the
frame below, except when
the lever is depressed for
the purpose of com-
pleting the circuit. A regulating screw is seen at the extremity
of the short arm of the lever, which graduates precisely the
amount of motion of which it is at any time susceptible.

1180. The third and last part of the tele-
Explain Fig. g rap h i s the registering apparatus, represented

in Fig. 174.

Here are two screw-cups, for the insertion of the wires from
i distant battery. An iron in the shape of a U magnet stands

Fig 174





at the left of the screw-cups, each arm of which is surrounded
by a helix or coil of wire, the ends- of which, passing down through
the stand, are connected below with the screw-cups. It will
then be seen that when the signal-key is depressed the electrir
circuit is completed, and that the electricity, passing through
fhe noils of wire, renders the U-shaped iron highly magnetic



iU JSUTKO- UAUNJET 1C TELL ./ .*A PH.
Fig. 17fc.




321 NATURAL PHILOSOPHY.

and it attracts the armature down. The armature IK fixed to
the shorter arm of a lever, and when the shorter arm is attracted
down, the longer arm, with a point affixed, is forced upward and
makes an indentation upon a strip of paper. The length of the
indentation on the paper will depend on the length of time that
the signal-key is depressed. When the signal-key is permitted
again to rise, the electric current is broken, the U-shaped iron
ceases to be a magnet, and, the armature being no longer
attracted, the weight of the longer arm will cause that arm to
fall, and no mark is made on the paper.

When the telegraph was first constructed, it was thought nec-
essary to have two wires in order to form the circuit. It has
since been found that the earth itself will serve for one-half the
circuit, and that one wire will alone be necessary to perform the
work of the telegraph.

1180. Fig. 175 represents the manner in which
Explain Fig. tne e ] ec t r i c telegraph is put into operation. -On
the left of the figure is seen the operator, with
the battery at his feet and his finger on the signal-key. From
one screw-cup of the battery extends a wire which traverses
the whole distance between two cities, elevated on posts for
security. In the distant city the wire reaches another screw-
cup to which it is attached, while from another screw-cup at 'the
same station another wire is attached, which extends back to the
operator first mentioned. The depression of the signal-key
forms a connexion between the two poles of the battery by
means of the wire, and the fluid will traverse the whole distance
between the two stations in preference to leaping over the space
between the two screw-cups. The right of the figure represents
the receiver of the information, reading the message which has
thus been imprinted by the point.

1182. In the preceding figures the mere out-

ExpUun fig. j- neg ^ ave h een given, in order that they may

be distinctly understood. To present the strip

of paoer bo that it may readily receive the impression, addi-



ELECTRO-MAGNETIC TELEGRAPH.



325



tional machinery becomes necessary. The complete registering
machine is shown in Fig. 176, in which S represents a large spool

Pig. 176.




on which the paper is wound, and clock-work with rollers to
give the paper a steady motion toward the point by which the
marks are to be made. A bell is sometimes added, which is
struck by a hammer when the lever first begins to move, in order
to draw the attention of the operator.

1183. .It will be recollected that this form of the magnetic
telegraph is familiarly known as Morse's, the machine making
nothing but straight marks on the slip of paper. But these
straight marks may be made long or short, at the pleasure of the
operator. If the key be pressed down and instantly be per-
mitted to rise, it will make a short line, not longer than a
hyphen. By means of a conventional alphabet, in wJijch the
tetters are expressed by the repetition and combination of marks
varying in length, any message may be conveniently spelt out,
so as to be distinctly understood at the distant station. Thesa
are the essential features of Morse's Telegraph.



ISO NATURAL PHILOSOPHY.

1184. It is necessary, in long lines of telegraphs, to combine tlia
efiects of several batteries to supply the loss of power in traversing
long circuits. This is done by local batteries or relays, as they are
sometimes called, familiarly known in connexion with Morse's tele-
graph. The use of the relays may be dispensed with by increasing
the power of the batery, or distributing it in groups along the line
It is sometimes divided by arranging one-half at each end of the
line For every twenty miles an addition of one of Grove's pint
sups should be made. The expense of acids for each cup for two
days does not much exceed one cent. For a line of telegraph
extending around the earth, twelve hundred Grove's cups would be
required, distributed at equal distances, fifty in a group.

1185. BAIN'S TELEGRAPH. The telegraph known by the
name of Bain's telegraph, the simplest now in use, differs from
Morse's principally in its mode of registering. It performs its
work by the decomposition of a saline solution. The pen or
point is stationary. A circular tablet, moved by clock-work,
under the point, receives the point in concentric grooves, and
the writing is arranged in spiral lines, occupying but little
space.

Explain Fig. 177 represents Bain's telegraph. The pen
Fig. 177. holder is connected with the positive wire of the
battery, and the tablet with the negative. The circuit is COIB

Fig. 177.




ELECTROMAGNETIC TELEGRAPH.



Fig. 178.



Dieted by paper moistened with a solution of the yellow prus-
siate of potash, acidulated with nitric or sulphuric acid. The
pen-wire is of iron. When the circuit is completed, the solution
attacks the pen, dissolves a portion of its iron, and forms the
color known as Prussian blue, which stains the paper. The
alphabet used by this line is the same in principle as that used
m the telegraph of Morse. The advantage of this telegraph
consists in^ the rapidity with which the disks at both ends are
made to revolve, by which a message may be communicated at
the rate of a thousand letters in a minute.

Explain H86. The
Fig. 178. CC H commonly
used in connexion with
Bain's telegraph is rep-
resented in Fig. 178. It
consists of a U magnet,
each arm surrounded by
a helix of wires, which,
when the current passes,
causes the armature to
be attracted and give mo-
tion to machinery, by
which a bell or a glass is
rung.

Explain 1187. Fig.

rig. 179. 179 represents the receiving magnet in its improved
form. The armature is
mounted on an upright
bar, directly before the
poles of the U magnet,
which is surrounded by
many coils of insulated
wire. In this magnet
the points of contact are
preserved from oxidation
by the use of platinum.




Fig. 179.




3z8 NATURAL PHILOSOPHY.

1188. HOUSE'S PRINTING TELEGRAPH. This telegraph differ?
from the other principally in its printing with great rapidity
the letters which form the message.

Explain 1189. Fig. 180 represents the mechanical part of
Fig. 180. House's telegraph. The operator sits at a key-board
gimilar to that of a pianoforte or organ, and, by depressing a



Vig. 180.




key, the letter corresponding with the key ie made to appear at
a little window at the top of the instrument, while it is at the
same time printed on a strip of paper below. The principle by
which this exceedingly ingenious operation is performed is
simply this : A given number of electrical impulses are given
for each letter. These impulses give motion to a wheel, so that
on the depression of a key the circuit will be broken at precisely
the point which corresponds with the letter. The machinery
by which this is effected is necessarily complicated and it falls
not within the province of this work to g6 fu ther into the
explanation. The whole process is described in Davis' Book of
the Telegraph, to which this volume is indebted for most of l he
particulars which have been giveii in relation to the subject.



ELECTRO MAGNETIC TELEGRAPH. 'j

The following history of the electric telegraph in this country is extracted
fex'iu. the Portland Advertiser, and deserves a place in this connexion :

" The electric telegraph, being used solely for the o^nveyance of news
and communications, is so intimately connected with posts and post-offices,
*hat a brief sketch of its rapid progress in the United States is here given.

" It is to American ingenuity that we owe the practical application of
the magnetic telegraph for the purpose of communication between distant
points, and it has been perfected and improved mainly by American scienc
and skill. While the honor is .due to Professor Morse for the practical
application and successful prosecution of the telegraph, it is mainly owing
to the researches and discoveries of Professor Henry, and other scientific
Americans, that he was enabled to perfect so valuable an invention

"The first attempt which was made to render electricity available for
the transmission of signals, of which we have any account, was that of
Lesage, a Frenchman, in 1774. From that time to the present there have
been numerous inventions and experiments to effect this object ; and, from
1820 to 1850, there were no less than sixty-three claimants for different
varieties of telegraphs. We will direct attention only to those of Morse,
Bain and House, they being the only kinds use.d in this country.

" During the summer of 1832, Professor S. F. B. Morse, an American, con-
ceived the idea of an elective or electro-magnetic telegraph, and, after
numerous experiments, announced his invention to the public in April, 1837.

" On the iOth of March, 1837, Hon. Levi Woodbury, then Secretary of
the Treasury, issued a circular requesting information in regard to the
propriety of establishing a system of telegraphs for the United States, to
which Professor Morse replied, giving an account of his invention, its pro-
posed advantages and probable expense. At that time * he presumed five
words could be transmitted in a minute.'

" In 1838, the American Institute reported that Morse could telegraph
the words ' steamboat Caroline burnt ' in six minutes. Now, a thousand
such words are telegraphed in two minutes.

" In 1844, Congress built an experimental line from Baltimore to Wash-
ington, to test its practical operation. That line was soon continued on to
Philadelphia and New York, and reached Boston the following year. Two
branches diverge from this line, one from Philadelphia to St. Louis, 1000
miles, the other from New York, via Buffalo, to Milwaukie, 1300 miles
long. One also, 1400 miles in length, goes from Buffalo to Lockport, and
from thence through Canada to Halifax, N. S., whence there is a continuous
line through Portland to Boston. The great Southern line, from Washing-
ton to New Orleans, is 1700 miles long. Another, 1200 miles, running to
New Orleans from Cleveland, Ohio, via Cincinnati. The best paying line,
it is said, is that between Washington and New York, which, during six
months of last year, transmitted 154,514 messages, valued at $68,499 ; and
the receipts for the year ending July, 1852, were $103,060. The average
performance of the Morse instruments is from 8000 to 9000 letters per
hour. The cost 01 construction, including wire, posts, labor, <fec., is about
$150 per mile. The Bain telegraph extends in the United States 2012
miles, and House's 2400 miles, making a total, with Morse's, of 89 lines,
embracing 16,729 miles. At how many way stations the magnetic current
is arrested and messages conveyed, we are not informed. Thus, in less
than nine years, from a feeble beginniMg, under the fostering aid of govern-
ment, have its wires apd news communications spread all over the country.

** The* astonishing results of the telegraph, victorious even in a run
against time, are remarkable in the United States. The western cities,
having a difference of longitude in their favor, actually receive news from
New York sooner by the clock than it is sent. When the Atlantic made
Ler first return voyage from Liverpool, a brief account of the newa was



NATUllAL PHILOSOPHY.

elegra;-htd to New Orleans at a few minutes after noon (New York ci;i>-) ;
and reacheJ its destination at a few minutes before noon (New Crleans
time), and was published in the evening papers of both cities at the same
hour. This is now a daily occurrence.

" Through its instrumentality (we mean no pun) Webster's deatb was
simultareuusly made known throughout the length and breadth of our
land, and the next morning the pulpits from Maine to New Orleans were
echoing in e'u'ogies to his greatness, and mourning his departure.

" The great extent of the telegraph business, and its importance to the
community, is shown by a statement of the amount paid for despatches by
the associated press of New York, composed of the seven principal morning
papers, the Courier and Knijuirer, Tribune., Herald, Journal of Commerce,
Sun, Times and Express. During the year ending November 1, 1852,
these papers paid nearly $50,000 for despatches, and about $14,000
*or special and exclusive messages, not included in the expenses of the
association.

"The difference between Morse's and House's telegraph is, principally,
that the first traces at the distant end what is marked at the other ; while
House's does not trace at either end, but makes a signal of a letter at the
distant end which has been made at the other, and thus, by new machinery,
and a new power of air and axial magnetism, is enabled to print the signal
letter at the last end, and this at the astonishing rate of sixty or seventy
strokes or brakes in a second, and at once records the information, by its
own machinery, in printed letters. Morse's is less complicated, and more
easily understood; while House's is very difficult to be comprehended in its
operations in detail, and works with the addition of two more powers,
one air, and the other called axial magnetism. One is a tracing or writing
telegraph, the other a signal and printing telegraph.

" The telegraphs in England are next in importance and extent to those
in this country. They were first established in 1845, and there are about
4000 miles of wire now in operation.

" The charge for transmission of despatches is much higher than in
America, one penny per word being charged for the first fifty miles, and
one farthing per mile for any distance beyond one hundred miles. A
message of twenty words can be sent a distance of 500 miles in the United
States for one dollar, while in England the same would cost seven dollars "

1190. THE ELECTRICAL FIRE ALARM. The principle of the electric
telegraph has recently been applied to a very ingenious pie?e of
mechanism, by which an alarm of fire may be almost instantly com-
municated to every part of a large city. Wires, extending from
the towers of the principal public buildings in which large bells
are suspended, unite at a central point, where the operator is in
constant attendance. On an alarm of fire in any locality, the watch
or police of the district goes to a small box, kept in a -onspicuous
place, which he opens, and makes a telegraphic communication to the
central operator, who, immediately recognizing the signal and the
district from which it came, gives the alarm, by making each bell
in connexion with the telegraph strike the number corresponding
with the district in which the alarm commenced. By this means
the alarm is communicated simultaneously to all parts of the city.
ThitJ ingenious application of scientific principles hap been in suc-
cessful operation In the city of Boston long enough to prove its
gieat value.



ELECTKOTY PIS PKOCESS. 331

*

1191. THK ATMOSPHERIC TELEGRAPH. An ingenious appar
atus, called " The Atmospheric Telegraph" has recently been
constructed by Mr. T. S. Richardson-, of Boston, designed to
send packages through continuous tubes by means of atmos*
pheric pressure An air-tight tube being laid between two
places, either under or above ground, a piston, called by Mr. R.
a plunger, is accurately fitted to its bore, behind which the
package designed to be sent is attached. The air having been
exhausted from the tube by engines at the opposite end, the
pressure of the atmosphere will drive the piston, or plunger
with its load, forward to its proposed destination.

This ingenious application of atmospheric pressure operates
with entire success in the model, and 'has been also successfully
tested in tubes that have been laid to the extent of a mile. Pa-
tents have been secured for the invention in England, Franje,
find other countries of Europe, as well as in this country ; and
a company is now forming for testing the principle between the
cities of Boston and New York. The air is to be exhausted
from the tubes by means of steam-engines, and there are to be
intermediate stations between those two cities.

1192. THE ELECTROTYPE PROCESS. This process, known by
the various names electrotype, electro plating and gilding, gal-
vanotype, galvano-plastic, electro-plastic and electro-metallurgy,
is a process by which a coating of one metal is made to adhere
to and take the form of another metal, by electrical agency.

1193. It is a process purely chemical and electrical, and the con-
sideration of the subject pertains more properly to the science of
Chemistry. As this volume has not professed to pursue a rigid
classification, it may not be amiss to give this brief notice of the
process.

1194. It consists in subjecting a chemical solution of one
metal to electrical action with another metal. A solution of a



Online LibraryRichard Green ParkerA school compendium of natural and experimental philosophy : embracing the elementary principles of mechanics, hydrostatics, hydraulics, pneumatics, acoustics, pyronomics, optics, electricity, galvanism, magnetism, electro-magnetism, magneto-electricity, astronomy : containing also a description of → online text (page 28 of 38)