Jr.NE 12, 1SS5.] 



♦ KNOWLEDGE 



495 



Ex. LXXII. — The oleclrilieil rod may ho held over a 

 quantity of bran, chopped straw, or Dutch metal cut in 

 small pieces (Ex. LXIX.), and laid on the bare table or 

 on a sheet of paper (Fig. 37). The small bodies will rise 

 towards the rod. (They will subsequently be driven away 

 or repelled, but of that more anon.) 



E.\. LXXriI. — Another experiment i.s to balance a 

 wooden lath (L, L' Fig. 38) about, say, 3 ft. long, 1.', in. 

 wide, and | in. thick, on an eggshell placed in an egg cup, 

 and then bring the electrified rod near one end of it; the 

 lath mav be very easily drawn round. 



Fig. 37. 



Ex. LXXIV. — Still another experiment is to balance 

 an nnrubbed i.e., unelectrified, rod of sealing-wax, itc, in a 

 suspended paper loop (Fig. 39), or in a carrier made by 

 bending a piece of brass or copper-wire into the shape 

 shown in Fig. 40, W being the wire, and R a ])iece of 

 ribbon, by which it is suspended. Round the ends of the 

 wire with a file, as nicely as pcssible ; or, solder them 

 together, afterwards rubbing down the superfluous solder, 

 and shaping them into the form shown in Fig. 41. The 

 suspended rod A B will be attracted by our electrified rod. 



Fig. 38. 



Ex. LXXV. — Hold the electrified rod oyer a person's 

 head, the hair (pre.suming the head chosen is not a bald 

 one) will be attracted, and assume a more or less erect 

 position. Dry hair answers best Some difficulty will, in 

 all probability, be experienced if the hair is at all damp. 

 Pass the rod over the face ; a peculiar creeping sensation 

 will be experienced, due to the attractive force exerted by 

 the electricity. 



Ex. LXXVI. — Place an egg-shell on a smooth, level 

 table or board, and bring the electrified rod near it ; it will 

 be attracted, and if the rod be slowly withdrawn along the 

 table the egg-shell will diligently and promptly trundle 

 along after it. 



Ex. LXXVII. — A .similar experiment, but upon a larger 

 scale, may be easily performed. Make a paper-drum. 

 Fig. 42. To do this, en', a strip of stout cartridge paper. 



about seven or eight inches wide and 19] in. long. J jet the 

 edges of the paper be square ono with the other, and, taking 

 one of the short edges, draw a lino parallel with it, but 

 within a quarter or three-eighths of an incii of the other 

 short edge. Bend this strip round and gum the unmarked 

 idge over the marked one, «lcttiiig the former coincide witli 

 the line on the other. A good cylinder may bj thus made. 



FiL'. -iO. 



Fig. 41 . 



The awkward part aViout the job is to attach the ends of 

 the drum. Cat two circular pieces of cartridge about 6.', in. 

 in diameter, and describe from the centre of each a circle of 

 Sin. radius. A rim, a quarter of an inch wide, will thus 

 be left round the paper outside the circle. With a pair of 

 scissors make a series of cuts across this rim, at intervals of 

 about half an inch. Gum the rim of one of the discs, lay 

 the drum over it so that it will coincide (as it should do) 

 with the circle, place a tumbler or any other convenient 

 round suUstance inside the drum, and pass it in succession 

 all round the lower edge, ht the same time pressing up 

 against it, jiiece by piece, the small sections of the rim. 

 Properly attended to, a good drum-end (A, B) will result. 



Fi'k. 42. 



Now for the other end (C, D). It is manifest that as we 

 cannot pass a tumbler or anything else round the inside, we 

 cannot guide the rim round the outside of the paper drum. 

 We may, however, eat-ily fasten the disc on the inside of 

 the drum. The rim having been duly cut, bend the pieces 

 forming the rim upwards, so as to give the paper an appear- 

 ance similar to that of the lid or cover of a round tin box. 

 Now gum the outer side of the rim, insert the disc just 

 inside the drum, and with the finger and thumVj press the 

 gummed outside of the rim against the inside edge of the 

 drum. The drum will now be ccmpii te, so far as its manu- 



