No. 24 cotton-covered copper wire and crowded the hole in the spool
full of wire nails _A_ (Fig. 198). I disconnected the wires from an
electric drop lamp and connected them to _b_ and _c_, the ends of the
wire from the spool. Our electric lighting circuit was what is called
the _alternating current_. I also had a second spool, _B_, precisely
like the first. The wires from this were connected to a miniature lamp,
_L_, such as is used at the switchboard of a telephone exchange. We
then screwed the drop-light plug into the chandelier and turned on the
electric current. I brought spool _B_ with the miniature lamp near to
spool _A_, as shown in Fig. 199, and when it was within a distance
of about two inches the little lamp lighted up to full brilliancy,
thus showing that while the electric current is passing in the wire
of spool _A_ its influence is not confined to the wire, but exhibits
itself in the region outside of the wire. To illustrate still further
this fact we substituted an electric bell in the place of the lamp
_L_, and when the spool _B_ was brought near to _A_ the bell rang. But
the most striking illustration was obtained when a telephone receiver
was put in the place of _L_. With this held to the ear while the spool
_B_ was brought toward _A_ a humming sound could be heard when _B_ was
about a foot distant from _A_. This sound grew rapidly louder as _B_
approached _A_, until, when the spool _B_ rested upon the spool _A_, a
sound like the peal of a pipe organ was heard all over the apartment.
The tone was very nearly that of the key on the piano which is two
octaves below middle _C_. I unscrewed the cap on the large end of the
telephone receiver, took it off, and moved the thin iron diaphragm to
one side, when it began to dance about at great speed. It was keeping
time with the dynamo, five miles away, which generated the electric
current. The dynamo changed the direction of the electric current sixty
times per second, and this made sixty vibrations per second. The dynamo
sent out ether waves which affected the telephone receiver, although
the receiver was not connected to the dynamo by wires.
To emphasize the fact that the dynamo had lighted the lamp, rung the
bell and made the telephone receiver hum without being connected with
them, I repeated all these experiments in a different way. Spool _A_,
connected as before with the electric lighting circuit, was concealed
beneath the table. For spool _B_ I substituted spool _C_ (Fig. 199), on
which the wire was wound so as to appear like a candlestick. On the top
of this was placed the miniature electric lamp screwed into a miniature
socket and connected to the wires of the spool. This "Witches'
Candle," as we called it, was sitting unlighted upon the table when I
called attention to the fact that if I moved it to a certain spot upon
the table it flashed into full light. (Of course this spot was directly
over spool _A_.) I moved it slowly away from that spot and its light
slowly grew dim and disappeared.
[Illustration: Fig. 199]
On the table was also sitting a cream pitcher in which I had placed
spool _B_ with a buzzer attached to it. Remarking that this pitcher
groaned for more cream whenever it was empty, and thus of its own
accord called the waiter, I moved it to the spot on the table directly
over spool _A_, when the buzzer gave forth a sound like a husky
bumble-bee shut up in a resounding bottle. At this signal my assistant
came in and took up the pitcher and placed my silk hat upon the table,
when it instantly boomed forth a base note two octaves below middle _C_
of the piano. Out of the hat I took a coil and the telephone receiver
and the mystery was solved.
[Illustration: Fig. 200]
In 1819 Hans Christian Oersted in Denmark (1777-1851) first noted
that the region about a wire carrying an electric current has an
influence upon a magnet. I will show this fact by a simple experiment.
I magnetize a stout sewing needle by drawing it from end to end across
the pole of a steel magnet, and by means of a triangular piece of paper
and a fine thread I suspend it a few inches above the table (Fig. 200).
I then lay upon the table a piece of wire parallel with the needle and
fasten one end of it to one binding post of a dry cell. Whenever I
touch the other end of the wire to the other binding post of the cell,
thus sending an electric current through the wire, the magnetized
needle is deflected at right angles.
This experiment, performed by Oersted, seems to have started Faraday
upon that wonderful series of researches which has resulted in giving
us the dynamo.
XXVII
WIRELESS TELEGRAPHY IN EARNEST
We had decided to let Harold make a trip to Europe alone. The first
message from him after his departure was a brief note to his mother
saying that they had had a turbulent voyage, but all had landed safely
upon the other side, none the worse for their experiences.
The next day a number of letters came to me from total strangers. One
of these ran as follows:
My Dear Sir:
Prompted by my own impulses, and urged to do so by the passengers under
my charge, I improve this first opportunity to express to you our high
appreciation for your noble but very modest son, to whom more than to
any one else we owe the lives of all on board our fated ship.
I am sending this direct to you both, because I understand a father's
heart and because the young man escaped as soon as we came to land,
without any of us learning his address. I beg you will communicate
to him the desire of the president of our company to meet him and
personally to thank him for his gallant conduct. I am also instructed
to say that whenever Harold desires to cross the ocean the best which
any ship I may command can afford will be his without charge.
Very respectfully yours,
-------- Captain.
S. S.
Another letter was the following:
My Dear Sir:
Permit me to congratulate you on having such a heroic and
self-possessed son. We, his fellow passengers, are, if possible, as
proud of him as you must be.
I fear that his account of the affair will not do himself full justice,
and so, with your permission, I will give you the full details as I
have gathered them from the passengers, from the crew, and from my own
observation.
During the last night of our voyage a thick fog closed about us. The
constant blowing of the fog whistle made the night dismal. Few persons
slept at all. About two o'clock in the morning the ship struck a reef,
and instantly it seemed as though every person on that ship reached the
decks at the same time. The water poured in and put out the fires. The
ship heeled badly, and it seemed that any minute she might slip off
the reef on which she was resting into deep water and go down. To add
to our horror fire broke out. It seems to have started in the wireless
operator's room.
Very much damage was done to the wireless outfit itself, and the
operator was badly burned, so much so that he was taken to the ship's
hospital suffering with many painful and dangerous wounds.
Meanwhile the flames spread rapidly and we were unable to summon help.
The crew and many of the passengers fought the flames, but with little
success.
In the midst of our despair word passed around the ship that an unknown
boy from among the passengers was sending the C. Q. D. message to
all the world by wireless. It was afterward learned that your Harold
was the youth. He had repaired the damaged apparatus sufficiently to
establish connection with a storage battery which he found, and, under
the captain's direction, was sending forth that hurry call for help
known to all the wireless fraternity and heeded by all sea-faring men.
I learned that your boy was not a regular operator, but that somehow
he had learned to send this message and also to send out the captain's
calculations of our position at sea. He was also able to detect that
his call had been heard and that help was coming, although he could not
understand much that came to his instrument in reply to his calls. I
learned, also, that he was one of the first to reach the operator's
room and to give assistance. He was himself badly burned, so much so
that one hand was being dressed by a nurse while he was continually
using the other to operate his instrument.
I can testify, my dear sir, that he appeared to be the calmest and most
self-possessed person on board that ship, as I saw him in the glare of
the dreadful flames which lit up the blackest night.
I am an artist and would like to attempt to paint that scene, which has
left its lasting impression upon my soul. I beg that you will allow
me to exhibit it for a time in several of our galleries and finally
present it to your family.
Help came none too soon. We were all transferred to other boats, but
the sea was rising, and scarcely had we reached a safe distance when
the burning ship slipped into the sea and disappeared.
I do not know by which boat your son reached the land. In the great
confusion I lost sight of him at last. He has doubtless communicated
with you by this time, and I shall esteem it a great favour if you will
put me in communication with him again.
In order that I may do justice to him in the painting I would like to
arrange with him a few sittings while he is in Europe.
Could you kindly send me a photograph of him which will assist me
somewhat?
Most sincerely and gratefully yours,
--------.
The letter contained several references to mutual acquaintances.
* * * * *
Harold's letters have been frequent and full of the pleasure he is
having in European travel, but the only thing he has said about the
voyage is that "it was not worth so much fuss."
[Illustration]
THE COUNTRY LIFE PRESS
GARDEN CITY, N. Y.
* * * * *
Transcriber's Notes:
Obvious typos and inconsistencies in spelling have been corrected:
p31. intrument -> instrument
p35. mantain -> maintain
p48. represents the [the] counter-electro-motive force
p64. 2 volts × .1 ampere = .6 watts. ->
6 volts × .1 ampere = .6 watts.
The correct voltage is deduced from the preceding paragraph.
p141. 55 ampere -> .55 ampere
p168. familar -> familiar
p173. preceptible -> perceptible
p229. - p230. countershaft -> counter shaft
p259. H_{2}SO^{4} -> H_{2}SO_{4}
p295. Note C refers to C´ not C´´
and these should be labelled C, and C,,
to denote octaves below middle C.
p316. electri-tricity -> electricity
p356. oufit -> outfit
Throughout the text:
The few cases of "volt-meter" have been changed to "volt meter"
which has been used for the majority of the text.
The single instances of watt meter and watt-meter have been changed
to wattmeter which has been used for the majority of the text.
The few cases of "electro magnet" have been changed to
"electro-magnet" which has been used for the majority of the text.
In the Table of Contents:
Chapter XII page number changed from 118 to 218
Chapter XV name changed from "Electricity from Chemical Action and
Chemical Action from Electricity" to match
text which reads "ELECTRIC CURRENTS FROM CHEMICAL ACTION AND
CHEMICAL ACTION FROM ELECTRIC CURRENTS"
In the Table of Illustrations:
"Operating a Switchboard" changed to match caption which reads
"Operating the Switchboard"
p63. The example of Morse code given is correct for "Original" or
American Morse. It has some differences from Continental or
International Code which is the current standard. The spacing of the
dots is significant.