Year: 1867

messages with rapidity. The method
adopted by Sir William Thomson is to
send several negative and positive currents
nearly at the same instant through the
cable: and the negative currents neutra-
lize each other, and the cable is ready for
second signal.


He was the inventor of the rejecting
galvanometer, an instrument for receiving
messages through long lines of telegraph
with weak currents of electricity. Most
of your readers are familiar with the tick,
tick, tick. of the telegraph, the combina-
tion of ticks making letters and words
but not SO are the messages between the
Old World and The New read by the op,
orators of the Atlantic cable. If you
suspend magnetic needle by a horsehair,
it will point north. If you cary coil of
wire around the needle at right angles
and send current of electricity through
it the needle will be DETECTED toward the
wire, just in proportion to the strength of
the current; but the moment the current
ceases the needle will point north again
A needle thus suspended will be DETECTED
by the least possible current Sir William
conceived the idea of attaching little
mirror of silvered mica to the needle
which moves with it, upon which ray
Of light from lamp shining through a
small hole in stationary piece of brass
is reflected by the mirror upon an ivory
scale about two feet off. The prass being
stationary and close to the end of the
needle and the rays of light streaming
through the hole will show the slightest
movement of the needle, be it the thous
audth part of an inch. Thus it is that
with thim5lefull of acid in the galvanic
battery you may discuss the news of the
Old World the speech Of Napoleon at
Lille; Of Garibaldi at Geneva, over your
toast and coffee at breakfast, before, in
point Of time with you, it has transpired
on this side of the Atlantic


Professor Thomson is practical in some
things and speculative in others He has
contributed many speculations to various
scientific and philosophical journals. and
has had sharp discussions with Professor
Tyndall on various points He is la.
borious student deep thinker, aud is
much respected by his associates. One Of
his speculations was given to the world a
year or two ago, and went the round of
the press, "On feeding the Sun" lie
contended that the heat Of the sun was
produced by a constant shower of rocks,
floating in space attracted by the sun,
and falling into it constantly and thus
generating heat. He prooed it by mathe
matcal demonstration. He has calcula
ted that the quantity of heat which would
re generated by the planets, should they
fall into the sun, would cause sufficient
heat to maintain the present heat of that
orb for several hundred thousand years
His conclusions on these points are moi
accepted by all his compecrs in science
Ia person he is tall, does not stand 81
erect as Sir Charles Lyell, is somewhat
round shouldered, has smooth, dark brown
hair, wide forehead, jutting eyebrows
mild blue eyes, an animated countenance
pleasant voice Like nearly all the 9th
er speakers. he hesitates and is at los
for words while speaking


PROFESSOR TYNDALL. e.t


A lecture was given by Professor Tyn
dali to the workmen of Dundee the othel
evening. Every seat in the great hal
was occupied by the engineers and me
chanics of this busy town, while on thu
platform were the magnates of the Associ
alton, who came not merely out of respoc
but to listen to their associate. You
readers know Of the lecturcs--that he i
Prof. of natural PHILOSOPHY at the Roy
al Institution, alsoat the Royal School 0
Mines in London--that he has written
clear and comprehensive work on tn
Conservation of Force" He is an olc
Alpine explorer, has climbed all the peak
Of the great chain, studied the might.
forces of nature above the clouds, and
watched with patient care slow moving
glaciers.


He is five feet ten in hight, 1.-the, agile
in the full vigor Of manhood, walks tn
street as if he were on wager, LOOKING
down, thinking earnestly, running hi
right hand through his wbiskcrs, no
knowing what be is doing He has


clear, penetrating eye, placid counfen
ance, and features sharp and angular
His lecture was on "Matter and Force" "
|, shall not attempt to make report Of th
lecture, which was SO simple in style tha
every one Of his vast audience could con
prehend it. although it dwolt upon the law