1878. ] Scientific News. 493 
_ schools he entered the Albany Academy, where he displayed a 
marked taste for scientific and mechanical branches, and he fol- 
lowed a natural bent when he afterward learned the watchmaker’s 
trade. In 1826 he laid aside his business to become an instructor 
at the Academy, and the next year began a series of experiments 
in electricity which introduced him to the notice of the world of 
scholars. Among his earliest discoveries was the fact that in the 
transmission of electricity for great distances, the power of the 
battery must be proportioned to the length of the conductor, and 
he was the first to magnetize a piece of iron ata distance or make 
use of electro-magnetism as a motor for machinery. In the last 
instance an oscillating iron beam was surrounded by a conductor 
or insulated copper wire. A current of electricity was sent 
through this in one direction, which caused one end to be repelled 
upward and the other attracted downward by two stationary mag- 
nets. The downward motion of the one end of the beam near 
its lowest point brought the conducting wires in contact with the 
opposite poles of the battery, which produced the reverse motion, 
so on continually. In a later arrangement the velocity of 
motion was regulated by a fly-wheel, and electro-magnets substi- 
tuted for the permanent magnets at first used. 
„In 1829 Prof. Henry prepared some electro-magnets of a power 
higher than any yet produced, and one which he afterwards con- 
structed on the same plan, and which will sustain thirty-six hun- 
dred pounds with a battery occupying only a cubic foot of space, 
Is still exhibited in the cabinet of the College of New Jersey. 
Continuing his investigations, he at length astounded his friends 
by applying the principle which we now see in use every day in 
the electric telegraph—making a bell to ring at one end of a wire 
a mile long by the transmission of a current from the other end; 
and in a paper printed in Silliman’s American Fournal of Science 
in 1831, he pointed out the possibility of employing such an 
agency for the instantaneous conveyance of intelligence from one 
