Lectures on electricity / by James Ferguson, F.R.S.

  • James Ferguson
Date:
1825
Catalogue details

Licence: Public Domain Mark

Credit: Lectures on electricity / by James Ferguson, F.R.S. Source: Wellcome Collection.

    15/112 (page 11)
    SECTION II. A Description of the Electrical Machine. 13. The electrical machine, mostly now in use, and as it is made in the greatest perfection by Messrs. Jones of Holborn, London,0 is represented by Fig. 1. of Plate I. in which A is a glass globe, E the handle or winch that turns it, by means of some wheel-work within the brass box C; and D is a cushion, covered with red Basil leather, for rubbing lightly against the globe. The cushion is supported by a brass spring E, and may be made to press more or less against the globe, by turning the screw F, forward or backward ; G H is the prime conductor, which is a brass tube with a round hollow ball at each end. The brass piece I is stuck into a hole in the ball G, and has several small forks of brass or steel, with sharp points, which almost touch the globe. The barrel of the conductor is put into the brass socket a, (which may be done after taking off the ball G,) and to this socket is joined the brass socket K, in which the upper end of the glass tube L is fixed with cement, and the lower end is cemented into the wooden foot, M. The glass tube being a non-conductor, insulates (as it were) the prime conductor G H, by cutting oft all con- ducting communication between it and the earth, tor, as the electric fire comes from the earth to the machine, and is put into motion and action by the rubbing of the glass globe against the cushion, and this fire goes round with the globe to the points I, which attract it and carry it to the prime conductor ; if the conductor were not insulated in this manner, or hung by silk lines, the fire would run as fast from it to the ground, as it received Note 6. Our Author introduces the name of Edward Nairne ; hut that very respectable Optician being long since deceased, the Editor believes that he is doing a real service to the scientific world by substituting the names of the above very ingenious artists, who have very much improved the machine.