Apparatus de- iht Spectator, half those of the original ; the other pavt« 

 diminishinfj as required by perspective. A wooden base 1, 

 1, on which the different parts of the apparatus are fixed, 

 must, during the experiments, be fastened to a table, by 

 proper vices, in order to make it steady while the instru- 

 luent is worked. On this base are solidly fixed two wooden 

 pillars, 2 and 3, the former of which is bored a little way 

 \ in, at the top 4, in a horizontal direction, for receiving one 



end of different spindles, as 5, the other end of which is 

 lodged in a groove at the top of the pillar 3, and projects 

 outwards to receive a winch 6, by which all the spindles 

 are made to revolve: they are prevented from moving 

 Dpwards in the groove by a piece of wood 7» placed 

 when they have b«en laid in, and outwards, by a ridge on 

 the apindle, bearing against the pillar 3 (as 5, fig. B.). The 

 prime-conductor 8, is made of a brass tube stopped at each 

 end; it is supported by a §-/a.?* pillar 9, covered with insu- 

 lating varnish, and fixed, "on the base 1, 1, by its own 

 wooden base 10. One end of this cowt/wc^o;- communicates 

 with the sphidles of whatever kind, by means of a very thin 

 slip of whale-bone covered with gilt paper, fixed to a brass 

 piece, which screws into the end of this conductor : thi$ 

 screw has some length, in order to move it backwards ot 

 forwards, so that the extremity 12 of the whale-bone slip 

 may attain the proper point of the spindle : the slip, which 

 ti elastic, presses against the spindle by a natural bent up- 

 wards. This part of the apparatus is the most difficult to 

 ftdjust ; the proper bearing of the extremity 12 of th6 

 > slip, on the different spindles, !nust be found by trials ; in 



general, it must bear, beneath the spindles, at a small 

 distance from the extremity l6 of the various rubbers. The 

 lither end of the primC'Conductor communicates with thd 

 go/rf-Z^o/" electroscope 11. 

 " There are different kinds of rubbers, but they are all 



fixed in the same manner to the apparatus: they consist, 

 either wholly, or in great part, of a very elastic brass lamina, 

 and differ only by that end of them, 16, which presses 6n 

 the spindle : the other eud enters laterally, and is fixed by 

 a wedge, inta a notch horizontally cut in the pftrt 15 of a 

 br^ss piece 13, held on the top of a gkss pillar, 14, 



covered 



