6-fr Mr. C. Binks on Electricity^ 



then have furnished to us a collection of data move valuable 

 in themselves, and better calculated perhaps than any yet ob- 

 tained to enable us to approach to the discovery, if not actually 

 to reveal the real nature of this peculiar but still mysterious 

 agent. 



Section III. — The Method of Investigation and preliminary 

 Experiments. 

 36. After some preliminary trials the following method was 

 selected for conducting these experiments. A wooden trough, 

 made water-tight by cement, and measuring 50 inches long, 

 7 wide, and 7 deep, had its upper horizontal edge marked off 

 from one end to the other into divisions of inches and fourths 

 of inches. At the end from which this graduation began, wag 

 fixed the zinc-plate to be experimented with, and the first di_ 

 vision, marked 1, was exactly one inch from the surface of the 

 plate itself, and the plate was about one inch from the extreme 

 end of the trough, which consequently was divided, beginning 

 from the zinc-plate, into 48 inches and fourths of inches, or 

 in all into 192 parts. At the zinc end was fixed the cup, hold- 

 ing mercury, in which the connexion between the two experi- 

 mental plates was to be completed. The zinc plate was con- 

 nected with a short wire, always of the same kind and length, 

 and each copper plate was soldered to a wire 5 feet in length ; 

 so that at whatever position the copper plate might be placed 

 within the trough, whether at the distance of \\h of an inch 

 from the zinc, or at 48 inches, or at any position intermediate, 

 the wire completing the circuit was always of the same length; 

 these experimental plates were retained at any required posi- 

 tion simply by bending their connecting wires twice or thrice 

 at right angles and thus fixing them over the sides of the 

 trough. It being intended to weigh the zinc-plate before and 

 after each experiment, or to collect the gas evolved from the 

 copper plate during the experiment, the former had its con- 

 necting wire so short as not to interfere with its being readily 

 weighed and replaced ; and the gas from the latter was col- 

 lected in a funnel-shaped meter having its open base so large 

 as to gather the whole of the gas sent off from the copper plate 

 of whatever size that might be. The long tubular part of 

 this meter was divided into tenths and fiftieths of a cubic 

 inch, and its entire capacity was about 1^ of a cubic inch. 

 The simple contrivance of a couple of strong glass rods, bent 

 twice at right angles, supported by the sides of the trough 

 and stretching across it, served as supporters for the meter, 

 moveable at pleasure, and by which it could be suspended at 

 any required position above the copper plate. The meter was 



