of the Cylinder Electrical Machine. 



253 



the packing-case, or a bottom for the universal discharger. 

 Another advantage is, that it is always ready for action at a 

 moment's warning, as there is nothing to do but to lift the 

 case off, and every thing is in its place. In Nairne's, or the 

 most approved construction, the negative conductor is always 

 in the way, whether it is wanted or not ; and the positive con- 

 ductor is not placed in the most convenient position. 



As in case of charging a battery it is proper to have a 

 small conductor, and in giving strong sparks it is necessary 

 to have a large one, and as a negative conductor is sometimes 

 required, the following arrangement will be found to answer 

 for all these purposes. The best form for the conductors is 

 oblong, of about the size of the rubber ; by this construction 

 these parts form very convenient stands of themselves : the 

 fork and round end next the cylinder may be dispensed with, 

 as the upper part of the positive conductor is cut with a Van- 

 dyke edge. The negative conductor is made a little smaller, so 

 as to fit within the positive when not wanted. When fixed at 

 right angles on the positive conductor, it nearly doubles the 

 power of that; and when fixed on the rubber, it forms the 

 negative conductor. One of its ends fits on loose, and has a 

 shank to it: this end forms the large ball for taking strong 

 sparks, when the small conductor is fixed vertically on the 

 large one. The charger passes through the ball at the end 

 of the conductor, and is fixed at any height by a screw: 

 it also connects the negative with the positive conductor. 

 This precludes the necessity of using the tops, balls, wires, and 

 chains of all the jars, and they are better without them : it 

 also connects the positive conductor with the earth. At the 



end is a female screw to secure the wood and coated points, 



plate, 



