ELECTRICITY. 37 ( J 



not pass through that part of the body which is 

 required to be electrified. Thus, any number of 

 shocks, precisely of the same strength, may be 

 given, without altering any part of the apparatus, 

 or having any farther trouble: and when the 

 strength of the shocks is required to be diminished 

 or increased, it is only necessary to diminish 

 or augment the distance between the balls B C, 

 which is done by slipping the wire C E forwards 

 or backwards through the spring socket that 

 holds it. 



It is almost needless to mention, that when 

 shocks are administered, it is immaterial whether 

 the patient stands upon the ground, upon the 

 insulating stool, or in any other situation whatever. 

 Neither is it always necessary to remove the clothes 

 from the part that is to be electrified, in order to 

 let the knobs of the directors touch the skin; for 

 except the coverings be too many and too thick, 

 (in which case, part of them at least should be re- 

 moved,) the shocks will go through them very 

 easily, especially if the knobs of the directors be 

 pressed a little upon the part. 



Plate 21. fig. 6. represents a useful instrument 

 to cure the tooth-ach. A is a flat square piece of 

 box-wood, about an inch broad, and a quarter of 

 an inch thick ; two longitudinal holes are made 

 quite through it, near its opposite edges; through 

 which the brass wires, a, b, c, and e f, are put 

 whilst they are straight; then fixed with sealing- 

 wax, and bent as in the figure, so as to receive 

 the tooth and gum between their points, c and f, 

 which must not be too sharp, for fear of hurting 

 the gum. When it is used, two chains, g and h, 

 must be hooked to the other ends of these wires, 

 and holding it on the gum, with the tooth between 



