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.

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    the fi re from the globe ; and then the whole machine would be good for nothing.7 14. These are all the parts of the electrifying machine itself:—the rest to be here described are only the dif- ferent parts of the apparatus belonging to it, for making experiments. And note, that when any of these is used, all the others should be set at least one foot from the machine. For, as the electric fire spreads about to some distance in the air, if any conducting substance be near any person or thing that is to be electrified, it will attract and carry off part of the fire, and make the experiment the more tedious and less success- ful.—So that, when either the balls O and P are used, or the crooked wire c d with the tly efg h i k, or the piece Q with the bells 11, S, T, or the Plates X and Y, or the feather b, or cotton m, it must be used by itself after all the rest are taken away.—And they are only put to the conductor in this figure, to shew how each is to be put thereto by itself, when an experiment is to be made w7ith it. 15. The holes in the prime conductor, for receiving the ends of the wires N, c d, and the feather b, should be well rounded off, and made smooth about the edges. For, if the edge$ are left sharp, they will be of the same nature as points, in throwing oft the electric fire • and this would spoil the experiments.-—I shall next describe the different parts of the apparatus belonging to my electrical machine, of which those in Plate II. are entirely new ; at least they are so to me. Note 7. From this it will be seen, that the prime conductor is a sort of magazine or reservoir for holding the electric fluid; and that if the particles of vapour, which are held in solution by the atmosphere, be deposited on the glass leg or silk, it will cease to retain this property. A reference to this fact will shew how necessary it is to keep the glass at a higher temperature than the room in which the experiments are made. An im- proved machine by which this important desideratum may be readily eilected, is introduced in the Supplement.