shown at b, a spark is obtained.
c is a battery formed by connecting together in series all the outer and all the inner surfaces of several jars, so that the united force of the whole is concentrated in the act of discharging.
The principle of the Leyden-jar was discovered by Muschenbroeck at Leyden in 1745, hence its name.
Von Kleist in Germany made the same discovery in the same year.
Gralath in Germany, 1746, contrived the electric battery by combining a series of jars; and finally Drs. Watson and Bevis, by covering the outside of the jar with tinfoil, brought it to the complete state in which we now have it.
The Leyden-jar is a condenser, its two coatings of tinfoil performing the parts of a collecting plate and a condensing plate.
1. A small balance.
2. A level (which see).
（Carding-machine.) A drum with cards on its periphery presented at the throat of a carding-machine, so as to catch or lick in the cotton filaments as they are<
t from the French government, and proceeded to erect works for the purpose.
This patent was in 1684 renewed for thirty years, but in 1688 Abraham Thevart succeeded in casting at Paris plates of a size which astonished all who saw them; they were 84 inches long and 50 broad, while the largest of those previously made had not exceeded 45 or 50 inches in length.
Among the more remarkable modern mirrors may be cited several of from 20 to 36 inches diameter.
One made by Villette was tested by Drs. Desaguliers and Harris.
It was composed of an alloy of tin, copper, and bismuth.
It was 47 inches in diameter, and was ground to a sphere of 76 inches radius.
Its effects were as follows: —
Tin was melted in3 seconds.
A silver sixpence7 seconds.
A half-penny of George III.34 seconds.
Granite vitrified54 seconds.
Copper ore8 seconds.
Bone, calcined4 seconds.
Tschirnhausen's mirror was 4 1/2 French feet in diameter; its focus, 12 feet.
It is supplementary to the usual cock at the condenser, to be used in the event of injury to the latter.
（Nautical.) a. An instrument invented by Drs. Hale and Desaguliers, to ascertain depths beyond ordinary deep-sea soundings.
It is a self-registering apparatus, in which the condensation of a body of air is cahe New York Hospital apparatus, for treatment of fractures of the thigh.
This is based upon the splint originally invented by Desault, and subsequently modified by Drs. Physic and Buck.
The outer splint is made in two pieces, one of which slides upon the other, so as to be adjustable to the length of the limb, is retained when adme class lies at the quarry, about a mile distant; it is 14 by 17 feet, and 69 feet long.
These stones are fitted so that a knife-blade cannot be thrust between.
Drs. Robinson and Thompson carefully measured these monsters.
See page 1404.
A machine for reducing to shape or<