137 
charges were found to have the oscillatory character observed with 
the Leyden jar; and by interposing several magnetizing helices 
with few and with many convolutions, Henry was enabled to get 
from a needle in the former the polarity due to the direct current, 
and in the latter that due to the return current, thus catching the 
lightning, as it were, upon the rebound.’’ In speaking, subse- 
quently, of the phenomena attending electrical oscillation in dis- 
charge, extending as they do to a surprising distance on all sides, 
Henry remarks: ‘‘ As these are the results of currents in alternate 
directions, they must produce in surrounding space a series of plus 
and minus motions analogous to, if not identical with, undula- 
tions ;’’ * a reference to modern theories clearly prophetic. In 
1845, he showed that the charge passed along the surface of the 
wire and not through its whole mass. 
As a fitting sequel to the investigations of Hare and of Henry 
which have now been detailed, and especially to the experiments of 
the former on ‘‘quantity’’ and ‘‘intensity’’ batteries, taken in 
connection with those of the latter on ‘‘ quantity ’’ and ‘‘ intensity ”’ 
magnets, it is interesting to notice the experiments upon the elec- 
tromagnetic telegraph which were subsequently made by two other 
members of the American Philosophical Society, John William 
Draper (elected in 1844) and Samuel Finley Breese Morse (elected in 
1848). The story is told by Professor Draper himself, in an address 
delivered, in 1853, to the alumni of the University of the City of New 
York. He says: ‘‘ Fourteen years ago, there stood upon the floor 
of the chemical laboratory of our University a pair of old-fashioned 
galvanic batteries. Like the cradle of a baby, they worked upon 
rockers, so that the acid might be turned on or off. A gray-haired 
gentleman had been using them for many years to see whether he 
could produce enough magnetism in a piece of iron, at a distance, 
to move a pencil and make marks upon paper. He had contrived 
a brass instrument that had keys something lke a piano in minia- 
ture, only there was engraven on each a letter of the alphabet. 
When these were touched, the influence of the batteries was sent 
through a copper wire and a mark answering to a letter was made a 
long way off. .... But, long after the telegraph instruments were 
perfected, it was doubtful whether intelligence could be sent to any 
considerable distance. It is one thing to send an electric current 
* Proceedings Amer. Assoc. Adv. Science, Albany meeting, 1851, p. 89. 
PROC. AMER. PHILOS. SOC. XXXII. 148. R. PRINTED DEC. 18, 1893. 
