5. The ingenious Abbè Nollet, whose theory has been more the subject of debate than all the others, before Dr. Franklin’s, supposes that in all electrical operations the fluid, (of which he admits there is but one) is thrown into two opposite motions; that the _affluence_ of this matter drives all light bodies before it, by impulse, upon the electrified body; and that its _effluence_ carries them back again. But he seems very much embarrassed in accounting for facts where both these currents must be considered as taking place at the same time, and in finding out expedients to prevent their impeding and interrupting the effects of each other. To obviate this great difficulty, he supposes that every excited electric, and likewise every body to which electricity is communicated, has two orders or kinds of pores, one for the emission of the effluvia, and the other for the reception of them. The Abbè maintained this hypothesis with a zeal and ingenuity worthy of a better cause. For it is manifest at once, that the existence of such kinds of different pores in bodies, is a mere gratuitous assumption. Our senses do not inform us of the existence of any such pores, nor have we evidence of any kind that they even exist at all, unless we consider it as evidence of their existence, that they are necessary to account for the appearances on which the Abbè grounds his theory. Yet this theory, with some modification, has been strenuously maintained, and has its advocates to the present day. They say that “in bodies positively electrified, there is a flux of electric matter, from their surface all round; that is, the fluid contained in their pores pushes out on every side, and communicates a similar motion to the electric fluid contained in the adjacent atmosphere. This must of necessity very soon exhaust the body of its electric matter altogether, if it was not instantaneously supplied after every emission. But this supply is immediately procured from the surrounding atmosphere. The quantity sent off is instantaneously returned from the air, and a _vibratory motion or struggle between the air and electric fluid_, immediately takes place. The positive electricity therefore consists in a vibratory motion in the air and electric fluid; and the force of the vibration is directed _outwards_ from the electrified body. In bodies negatively electrified, the fluid contained in the neighbouring atmosphere is directed _towards_ the body so electrified. But it is certain, that this motion inwards cannot be continued unless there is also a motion of the fluid outwards from the body. In this case also, there is a vibratory motion, but the force of it is directed _inwards_, and as the source of it lies not in the body, but in the surrounding atmosphere, it manifests itself somewhat less vigorously.” We have taken this account of the modification of the Abbè Nollet’s theory from one who firmly believed it. But we cannot pretend to controvert it, because, (as Dr.