Ptcht Elt^rleal Machlnt. 



II. 



Defcription ef a Pocket Ribhand-machlne, for charging a fmall coated Phial -with E/cnHci/y. 



By y. Till. Ulloustone. 



X IG. I and 2, PI. I, are reprefentations of this inftrument of its real fize ; A B C D, fig. i and 

 2, are two flat mahogany boards, each three inches long, two inches broad, and three-eighths 

 of an inch thick. In the holes E and F, fig. 2, which are two inches from each other, and 

 equidiftant from the fides and ends of the boards, are glued faft two cylindrical pins of box- 

 wood, efich one-fourth of an inch in diameter } thefe pins projeft about one inch and a quarter, 

 perpendicularly, from the oppofite furface of the board, and have their ends formed into mab 

 fcrews about one-half of an inch long. Two cylindrical wooden pins of one-eighth of an 

 inch in diameter, but without fcrews, are fixed at each end of tha-fame board, and in the fame 

 tranfverfe lines with the other pins, but near the fides, as at G H I J. They ftand parallel 

 to the other pins on the fame furface of the board, and are about a quarter of an inch Ihorter. 

 Thefe pins pafs through fix holes in the board, fig i, when both boards are applied together. 

 Two flat nuts of boxwood, K and L, fig. i, of five-eighths of an inch in diameter each, arc 

 fcrewed upon the middle pins to prefs the boards together. Each board has one of its faces 

 covered with a cufhion, confifting of fix or eight pieces of flannel flightly ditched together, 

 with perforations for the pins to pafs through. The cufhions are covered with a mole-fkiii 

 l^id with the fur outwards, and the hair of each inclining to tiie edges of the boards, in the di- 

 reftion of the arrow in fig. i ; holes being alfo made through the Ikins to admit the pins. 

 When the boards are fcrewed pretty clofe together by means of the nuts, with the cufliion* 

 between them, the redundant edge or border of each fkin is glued to the edge of its refpe£tive 

 board, and they thus completely form two elaftic cufhions. A piece of brafs wire, about one 

 tenth of an inch in diameter, is bent into the form M N O, fig. 2, and fixed upon the inner 

 fide of this board, which is faced with the fur, and in the fituation reprefented in the drawing, 

 by means of two fcrews which pafs through pieces of flat brafs, foldered on the wire. To 

 the parts M S O T of this wire, a tin tube is foldered, open at both ends, and fitted to re- 

 ceive the lower part of a very tliin ounce oj- ounce and half phial or jar, coated on both fides 

 with tin-foil, excepting 1 1 of an inch of its top. This phial, when placed firm in the tin tube, 

 has its wire parallel to, and i^ inch from, the fide of one of the boards, and likewife in the 

 fame plane with that produced by the contadl of the two cuflbions. The wire proceeding 

 from the infide coating of the phial is fixed firmly in its neck, by means of a narrow filk rib- 

 band dipped in melted eledlric cement, and rolled lightly round the fame wire to a proper degree 

 of thicknefs. The fpace U V X W, fig. i, is without tin, and is rather more than half the 

 circumference of the tube. Thus the charged phial may be removed from the machine, 

 without the hazard of difcharging, by pufliing it forward a little with the thumb applied 

 againft its bottom, and then taking hold of it by its coating. R is a curved lY're, with a 

 ball to it, which by moving on E as a centre, and ftanding at any angle, it is raifed to anfwer 

 the end of an eleftrometer and difcharger of the phial. The figure of an arrow is made on 



the 



