9* 



ON THE ELECTRIC COLUMN. 



breadth, but cut across the Jihres, produced much less di- ^ 



tninution ii^ th<' divergence. Dr. Lind found probably the 



cause of this d'uTerence, assigning it to the situation of the 



resinous substance within that wood : it does not belong to 



thf fibres themselves, since they transmit easily the e.'ectric 



Jlui.l; it is lodged between the Jihres, aid us forms an 



impt'diment to the passage of \\it Jiuid froai Jibre to fibre 



in the slips cut a< ross them. 



TriaHonthe When these experiments are made with the view of try-.. 



msuUtinp^;ow- jp2: the i/?««/ii/ii?ff property of bodies, still more prec;iutiou 

 ers of bodies. . * • , • , • , , . i .- .. / i- 



IS required in placing them on the hooks oi the column : tor 



the bodies fit for this use being fundamentally imjurnuable 

 to the electric matter, their electric state is changed, more 

 or le?s permanently, hy friction', and this in the manner 

 vhirh 1 intend to explain in a future paper. As, however, 

 the^' can hardly be handled without some frictio7i, they act 

 ■upon the column by their ivfuence (an effect that I shall -, 

 show directly hereafter), and their insu/ating property can-« 

 uot be observed, on account of the disturbance which they 

 prpduce in the state of the column itself. These bodies 

 therefore must remain a little time untouched on the brackets, 

 and be there breathed upon, in order that the woeVwre of 

 the breath may dissipate their electrization; serving as a 

 conductor for their whole surface to the ground, through the 

 brackets; and when the tnoisture is evaporated, the rods 

 are taken up there with the insulating hooks, and thus ap- 

 plied to the column. 



These experiments are particularly viseful for a better 

 knowledge of insulation, a point very important in the con- 

 struction of e'ectric apparatusses ; for many experiments 

 fail for want of a complete insulation; and I do not know 

 of any shorter and surer method of trying the insulating 

 faculty of varnishes laid on glass for this purpose, ths^n that 

 of applying to the column rods of glass covered with them. 

 I shall also give only a geneiivl idea of this class of trials 

 pnder the following head. 

 Exp. 12. Erp. 12. It is very seldom, that a naked glass rod, be- 



ing placed on the hooks of the column, does not sensibly 

 diminish, in a little time, the divergence in the electro- 

 scopes, by transmitting sowly aome electric Jiuid from A 

 to l>: but this is more or less, according to the nature of 



the 



