.510 



ELECTRICITY. 



Inflating 



Practical the sixe of m ouill, for the purpose of attaching wires 

 and balls, ana other pieces ot apparatus, must have 

 their edge* well rounded and smoothed off. To tin- 

 aide or end of tin- conductor, according as its side or 

 end is presented to the cylinder, is fixed a row of me- 

 tallic point", which receive the electricity from the 

 globe or cylinder, and which are placed at the distance 

 til' one-eighth or one-tenth of an inch from its surface. 

 These points are seen in Figs. 1, 2, and 5, as placed at 

 the extremity of the conductor. The length ot the con- 

 ductor is, in general, a little greater than that of the glass 

 cylinder, and i'.. diameter alKiut .j of that of the cylin- 

 der. It must be insulated upon a glass stand, having 

 its non-conducting power increased by a coating of 

 sealing vrax dissolved in spirit* of wine, or the glass pil- 

 lar may be heated, and then rubbed over with the wax. 

 As gum lac is a better conductor than sealing wax, it 

 might be substituted in its place. On the back of the 

 rubber, as represented in Fig. 3, there is often fixed 

 another conductor, called a negative conductor, and sup- 

 ported, along with the rubber itself, upon a varnished 

 pillar of glass. 



A necessary part of the electrical apparatus, is an in- 

 tulaling ttool, which is nothing more than a piece of 

 mahogany, or any other wood, supported upon 4 glass 

 feet. Sometimes it is made large enough to hold a 

 common chair, but, in general, it has only that .size and 

 strength which will allow a person to stand upon it 

 with safety. 



When the electrifying machine is alxnit to be used, 

 the greatest care must be taken to free it from all par- 

 ticles of dust, and to dry it thoroughly, by rubbing 

 every part of the apparatus with a piece of flannel or 

 woollen cloth made excessively dry, by being toasted be- 

 fore a good fire. The amalgam must then be laid upon the 

 cushion, and spread uniformly with :i piece of leather, 

 tion of elec- go aj j ug t tg reac h the junction of the silk glass with 

 the cushion. If the machine has already been in use, 

 the old amalgam should be carefully taken off; the 

 silk flap should be freed from any dust or amalgam that 

 may have lodgedupon its surface, and from the black spots 

 and lines which almost always accumulate upon the cy- 

 linderor plate of glass, particularly after a recent applica- 

 tion of the amalgam. M. Wolff, of Hanover, rt'com- 

 mends strongly that a piece of fine white paper should 

 be placed above the amalgam, so as' to be interpo- -d 

 between the rubber and the glass. Mr Nicholson has 

 deduced, from a variety of trials, the following gene- 

 ral directions for producing the most powerful effects 

 Nicholson's from electrical machines. His directions refer to that 

 kind of rubber in which the silk flap is attached to 

 the lower edge of the cushion, and returns back over 

 its surface. After the cylinder is cleaned, and the 

 silk well wiped, grease the cylinder by turning it 

 against a piece of leather containing the grease from a 

 tallow candle. Continue to turn the cylinder till the 

 silk flap lias wiped off as much of the grease as to 

 render the glass semi-transparent. Some of Higijins' 

 amalgam must be spread upon a piece of leather till it is 

 uniformly bright. The leather must then be held against 

 the turning cylinder. The friction will immediately 

 increase, and the leather must not be taken away until 

 the friction has reached its maximum. When thcsi- di- 

 rec.tions arc implicitly followed, Mr Nicholson found 

 that the excitation was extremely powerful. With a 

 cylinder 7 inches in diameter, and a cushion 8 inches 

 long, three brushes of light escaped at once from a .'! 

 inch ball. A <l inch cylinder, and an 8 inch cushion 

 occasioned frequent flashes from the round end of a 

 conductor 4 inches in diameter. With a 12 inch cy- 



r.encral it- 

 marks on 

 the excita- 



cxpen- 

 nienu on 

 the excita- 

 tion of ma. 



Under, and a rubl>er of "i inches, a 5 inch ball gave Pr 

 frequent flashes upwards of 11 inchc- l<m : _'. ,-in.l gome- \^1 _ 

 times Hashes were emitted from a () inch ball. '1 'lie 7 

 inch cylinder afforded sp-irk of luj inches at the be-!, 

 and the f) inch cylinder, which had not a sufficiently 

 high sup)Mirt, sent flashes to the table which was 11 

 inches distant. 



I pinasse, P!,ll. Trims. 176?, p. 186. Iliggins. 

 Pint. Train. 177S, p. 861. Kienmayer, in l! 

 Journal. vol. \x\iii. p. <;(>. Singer's Elementl nf 1 

 tricity, p. 52. Note. Nicholson, Phil. Trans. 1780. p. 

 265. 



SECT. I. On Bkchifbitg M/icl/ines ninth' of Globes ami 

 Cylinders of Glatt. 



1. Detcri/ition of the common Cylindrical Elfclrififine 

 Machine, with a simple Handle. 



Tun common electrifying machine, con-istin^ of a ' 

 glass cylinder, was first introduced !>y the drman-. 

 and notwi-hstanding the many changes which it tau> "' 

 undergone, it is still the cheapc-t, the .-'.nple-t. and the 

 most ]>erfect of all the electrifying machines formed of 

 glass. 



This machine is represented in Plate CCXI.VII. 1 ig. p, An , : 



1. where AB is the cylinder of glass, supported upon rcxi.vn. 

 the two pillars E, F, made either of glass or baked wood. '"'B- ' 

 These pillars are firmly fixed into a board or stand (iH, 



which is screwed to a table by means of the two clamps 

 shewn at X and Z. The cylinder of glass receives its 

 rotator}' motion, by means of the simple \vinchor handle 

 W. The rubber is represented at m, supported on a 

 pillar R, fastened into the board OH. 15y m iii-ofthu 

 screw S, this pillar can be brought towards S, so as to 

 make the rubber m apply w ith sufficient tightness to tin- 

 cylinder. The silk Hap, attached to the rubber, is shewn 

 at no. The prime conductor CD is placed upon an in- 

 sulating stand, and receives the electricity from the cy- 

 linder, by means of the metallic points shewn at/i. The 

 jar and discharger,, attached to the conductor, will bi 

 afterwards described. 



2. Description of the common Elect rifi/iai: Machine, it 



a Multiplying Wheel. 



This machine is represented in Fig. 2, and is aln.-ost Cmr: 

 exactly the same as the last, excepting in the n trlcctrituug' 



for giving the cylinder a rotatory motion. 1-i-Undof " 

 . i i L i i \\- i 11 win arnul- 



doing this by the simple winch \\ , as in Fig. I, a small ,1,,^,,.,, 



wheel n' is fixed on the axis of the cylinder, which pi 



jects beyond the pillar F. Helow this, and fa-tened l" '' 



the pillar F, is a large wheel W, which has a motion of ' ' -\'- v " 



rotation round the fixed axis x, by means of the handle 



seen above H. A string being passed over the wheel, 



as shewn in the Figure, the revolution of the lav. 



W will give a rapid motion to the suuill wheel ie. 



thus produce more, electricity in a given time. (M-OO\CS 



of different diameters are cut around the wheels W and 



it, in order to tighten the string when it becomes li 



by frequent use. In this drawing, we huve shewn a 



different construction of the rubber; instead of being 



pressed against the cylinder by a screw S, as in Fig. 1. i-'jg. ]. 



the pillar R is fixed into .1 slider, which can be pulki! 



out and in, and tightened in any position by the screw 



nut N. The other letters in this Figure refer to the 



same parts as those described in the preceding article. 



3. Description of Nairnc's Patent Electrifying Ma- 



chine. N.-irn<"]ia. 



i uv:n- 



This machine, which is both simple, compact, and 

 powerful, and has been much used for medical pur- i 



