Lamp Furnace.-^Meafures of Elefirictty, 2jf 



moveable piece H, which ferves to fufpend the velTeJs in a convenient (Ituation, or to fecure 

 their pofition. The whole fupport is attached to the fquare iron ftem of the lamp by a 

 piece of hard wood I, which may be fixed at any required fituation by its fcrew. 



K reprefents a ftand for the receivers. Its moveable tablet L is fixed at any required 

 elevation by the wooden fcrew iVI. The piece which forms the foot of this ftand is fixed 

 on the board N ; but Its relative pofition with regard to the lamp may be changed by 

 Aiding the foot of the latter between the pieces O O. 



P, another ftand for the pneumatic trough. It is raifed or lowered, and fixed to its 

 place, by a ftrong wooden fcrew, Q^ 



R is the tube of fafety, or reverfed fyphon, invented by Citizen Welter, and defcribed 

 rn the third cahier of the Journal of the Polytechnic School, p. 437 *. 



F/'g. 2. fliews the lamp furnace difpofed to produce the faline fufibn ; the chimney oP 

 glafs fhortened ; the fupport D turned down ; the capfule of platina or filver, S, placed on- 

 the ring very near the flame. 



I''ig. 3. The fame part of the apparatus, in which, inftead of the capfule, a very thin and 

 finall crucible o£ platina,. T, is fubftituted,, and refts upon a.triangle of iron wire placed onp 

 the ring. 



Fig. j^, exhibits the plan of this laft difpofition; 



IV. 



^h Account of fame Experiments mnde hy Mr. JoHN CUTHBERrsON, with a Vieiv to deter*- 

 mine an unequivocal Method of afeertaining the Power of eledrical Machines.. 



He 



-OWEVER great the influence and probable importance of eledricity may appear irv. 

 a large clafs, and perhaps in the whole of natural phenomena, we ftill find that a number 

 of fundamental experiments remain to be made. Among thefe there is fcarcely a more de- 

 Crable objeifl than to determine the degree of excitation or quantity of eledlrlcity afibrded 

 by machines, in proportion to the furface expofed to fridion. When phllofophers en.r 

 deavQur to communicate to each otlier the indications of power in their refpetlive eleflrlcal^ 

 apparatus, they either defcribe the length and appearance of the fimple fpark from a con- 

 dudtor, or the explofion from a certain meafure of coated furface, or elfe the diftance to 

 which the attractive power of the prime conduQor is rendered perceptible upon a thread 

 or pendulous body. The firft of thefe methods is fubjeft to variation from the magnitude 

 of. the conductor itfelf, the figure of its termination, and particularly that undulation of 



* And alfo in the id vol: of the Annales de.Chitnie, p. 3 1 ». This apparatus ferves, in a great mealiire, to 

 prevent the bad effcfts of having the veff'-ls either perfti'^ly clofed or perfectly open. Slippofe the upper bell- 

 ihaped veffcl to be nearly of the fame magnitude as the bulb at the lower end of the tube, and that a quantity 

 of water, or other fuitable fluid, fomewhat left than the contenisof that veffel, be poured into the apparatus-: 

 In this fituation, if the elafticity of the contents of the vcffels be kfs than that of the external air, the fluid will 

 defcend into the bulb, and atmo'phcric air will follow and pals through the fluid into the vtflels : but, oa 

 the contrary, if the elafticity of the contents be greater, the fl»]|d will be either fuftaintd in the tube, or driven 

 into the bell-fliaped veffel; and if the force be ftrong enough, the gaftous matter will fafs through..the liuid,, 

 {H)d ip part cfcape, N-. 



*• which 



