Professor Leslie on Electrical Theories. b 
neglected the cultivation of this subject, or have considered it as 
only an amusement or a relaxation from severer studies.— At 
present, I shall examine the opinion commonly entertained in 
regard to the action of Electrical Points , and shall take a fu- 
ture opportunity to communicate some experiments and obser- 
vations on other parts of Electricity. 
In the communication of electrical influence from one body to 
another, there is evidently a certain portion of time required. 
Thus, if a plume of glass-th reads be stuck in the prime conduct- 
or, it will gradually swell and expand as the cylinder is turned 
round ; and if, while in this state, we make a sudden connexion 
with the ground, we shall perceive a gentle and slow collapse. If 
a lock of silk or a feather be tried in this way, the effects will be 
the same, only rather quicker in their production. But there 
are other bodies, the metals particularly, in which the electrical 
communication seems instantaneous, or takes place in a time 
shorter than the interval between our sensations, and therefore 
observation. We have other instances in Physics 
that are exactly similar. Thus, it may be shewn that every spe- 
cies of motion is impressed gradually anti in time; yet, in most 
cases, this circumstance entirely escapes our notice, though in 
others it cannot fail to be observed. Accordingly, forces, be- 
sides the Accelerating or Retarding , have been divided into the 
Impulsive, — a division which seems to have no foundation in Na- 
ture. But the electricians have gone a more unjustifiable length : 
they have discriminated substances into Conductors and Non-con- 
ductors ; whereas no body has been found incapable of com- 
municating the electrical virtue. The only difference consists 
in the celerity with which the effect is produced ; and were 
conductors properly classed, it would be found, in the descend- 
ing range, that the velocity of transmission diminishes by insen- 
sible shades. 
To the class of exceedingly slow conductors, we must refer the 
atmospheric air itself ; for a glass tube, which includes it, is appa- 
rently as slow in conveying the electrical virtue, as a glass-rod 
of the same dimensions. But air is a fluid which acquires consi- 
derable motion from the slightest impression, and this extreme 
volubility alone may fit it, in a certain degree, for making the 
totally eludes 
