Charles Grafton Page. 5 
covering one remaining step of primary importance in the im- 
provement of these machines. The electro-magnet and induc- 
tion coil in which he first, and several months earlier, used the 
shortened BE Pac circuit, was in this particular, very nearly a 
ody’s communication to Mr. ‘Sturgeon and Mr. Clarke, is sta- 
ted by Sturgeon to have been made one or two weeks before 
the Bristol meeting of the British Association. This meeting 
took place Aug. 234, 1836, and Callan’s last mentioned paper 
was dated Maynooth, Aug. 23d, 1836. While, therefore, there 
: appears no doubt that Prof. Callan was quite independent of 
} Prof. Page in making this important step, it is clear that pri- 
F ority belongs to the ‘latter. 
I We have thus dwelt at some length upon this subject be-~ 
: cause we have not found it possible otherwise to do justice to 
Prof. Page, and to all most directly concerned. 
Related to this principle, another discovery of interest which 
Prof. Page made in the same series of experiments was that 
: the intensity of the shock was increased by making the break 
of the battery circuit (over mercury) take place under a non- 
conducting liquid. The question suggests ne whether this 
observation might not deserve renewed attentio 
| In the course of his experiments with the flat spiral he ob- 
: tained the spark and the shock from a thermo-electrie current 
: (this Journal, I, vol. xxxiii, p. 118), and thus added one more to 
| the links which Faraday had already supplied to demonstrate the 
identity of thermo-electricity, voltaic electricity, and statical 
electricity. He also succeeded in charging a leyden jar by 
means of the induced current, a result belonging to that class 
of facts which warrants the use of the term current as cor- 
rectly expressive of the actual relation existing between stati- 
cal electricity and voltaic, or dynamic electricity, and after hay- 
ing increased his flat spiral to the length of 320 feet, he even 
succeeded in doing this with a voltaic battery of a single pair. 
It should also be mentioned that he projected the induced cur- 
rent (this Journal fad (Oct., 1837, p. 355) between charcoal a 5B) 
points “‘ before con 
To 
rof. Page es alongs the adaptation to the induchon cou 
coil, of the self-acting g circuit breaker, that is, a circuit breaker 
: operated by the current itself, The circuit breaker he first 
__used (1836), was Barlow’s spur wheel, which turns between 
the poles of a permanent horse-shoe magnet, Soon afterward, 
