450 PHILOSOPHICAL TRANSACTIONS. [aNNO 1788. 



also intended to manifest small, and otherwise unperceivable, quantities of elec- 

 tricity; but from the experiments and observations Mr. C. since laid before the 

 R. s. he thinks it clearly shown, that this doubler cannot be of any use, on ac- 

 count of its being naturally always electrified. In the same paper he mentioned 

 a method which he had used for collecting diffused quantities of electricity. Since 

 that time he has improved the method; and, after several alterations, constructed 

 an instrument for the purpose, which is deemed free from all those faults which 

 render M. Volta's and Mr. Bennet's instruments of little, if at all of any, use. 



The properties of this machine, which from its office may be called a collector 

 of electricity, are first, that when connected with the atmosphere, the rain, or 

 in short with any body which produces electricity slowly, or which contains that 

 power in a very rarefied manner, it collects the electricity, and afterwards renders 

 both the presence and quality of it manifest, by communicating it to an elec- 

 trometer. 2dly, This collecting power, by increasing the size of the instrument, 

 and especially by using a 2d or smaller instrument of the like sort to collect the 

 electricity from the former, may be augmented to any degree. 3dly, It is con- 

 structed, managed, and preserved with ease and certainty; and it never gives, 

 nor can it give, he thinks, an equivocal result. 



Fig. 1 and 2, pi. 6, exhibit 2 perspective views of this collector. Fig. l 

 shows the instrument in the state of collecting the electricity; and fig. 2 shows 

 it in the state in which the collected electricity is to be rendered manifest. An 

 electrometer is annexed to each. The letters of reference indicate the same 

 parts in both figures, abcd is a flat tin plate, 13 inches long and 8 inches 

 broad; to the 2 shorter sides of which are soldered 2 tin tubes ad and bc, which 

 are open at both ends, de and cp are 2 glass rods covered with sealing wax by 

 means of heat, and not by dissolving the sealing wax in spirits. They are ce 

 mented into the lower apertures of the tin tubes, and also in the wooden bottom 

 of the frame or machine at e and p, so that the tin plate abcd is supported by 

 those glass rods in a vertical position, and is exceedingly well insulated, ghilkm 

 and Nopv are 2 frames of wood which, being fastened to the bottom boards by 

 means of brass hinges, may be placed so as "to stand in an upright position and 

 parallel to the tin plate, as shown in fig. 1 ; or they may be opened, and laid on 

 the table which supports the instrument, as in fig. 2. The inner surfaces of 

 those frames from their middle upwards is covered with gilt paper xy ; but it 

 would be better to cover them with tin plates, hammered very flat. When the 

 lateral frame stands straight up, they do not touch the tin plate; but they stand 

 at about -i- part of an inch asunder. They are also a little shorter than the tin 

 plate, that they might not touch the tin tubes ad, bc In the middle of the 

 upper part of each lateral frame is a small flat piece of wood s and t, with a 

 brass hook; the use of which is to hold up the frames without the danger of 



