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LXII. On a new Electrical Machine. 

 ByW. Holtz of Berlin*. 



[With a Plate.] 



I EXPERIMENTS with the electrophorus led me to the idea 

 ^ of otherwise turning to account the theory of this appa- 

 ratus. As this theory contains a very rational principle of de- 

 veloping electricity, I proposed to myself to apply the same 

 principle to the construction of an electrical machine. It has 

 been found not only that such machines are possible, but that, 

 with a moderate expenditure of force, they far exceed ordinary 

 machines in their quantitative effects. It' is the object of this 

 paper to describe accurately the construction and mode of action 

 of a simple apparatus of this kind. 



A steel shaft 9 inches in length (fig. 1, Plate V.) is supported 

 at its ends in a horizontal position, and can be set in rapid rota- 

 tion by means of a cord and a pulley which is turned by a winch f. 

 In the middle of the axis, and fastened exactly at right angles 

 to it in a mounting of vulcanite, is a round glass disk of 15 

 inches diameter. The mounting is best made of two smaller but 

 thick disks, of which one is fixed on the axis, and the other can 

 be screwed on it. The glass disk must be accurately centred, 

 and chosen of very thin and flat plate glass. 



Another round disk, but 2 inches larger in diameter, which 

 may consist of flat window-glass, is provided in the middle with 

 such an aperture that it can be fastened parallel to the first 

 at about the eighth of an inch distance. This is effected by 

 means of four horizontal bars of vulcanite provided with small 

 moveable rings, which touch the edge of the glass at about equal 

 intervals. In this disk are two deep notches of peculiar shape, 

 and it is coated in two places w T ith paper ; the two notches, as 

 well as the two coatings, are exactly half a turn apart and so 

 placed that in each case a notch directly precedes a coating. 

 The form of the notch is best seen from the drawing : its 

 greatest breadth and depth amount to 4 inches. The coatings, 

 which are on both sides of the glass disk, are of the same length, 

 but do not pass beyond the edge of the rotating disk. The 

 breadth of the outside part is 2 inches, that of the inside is 

 about half as great. From the latter, two pointed pieces of 

 drawing-paper project to about the middle of the notch. 



In front of the rotating disk, parallel to the axle, and also 



* Translated from Poggendorff' s Annalen, No. 9, 1885. A notice of an 

 imperfect form of the instrument, communicated by Professor Poggendorff, 

 has already appeared at page 159 of this volume. 



f It is very convenient to have an arrangement for treading, so as to 

 leave the hands free. 



Phil Mag. S. 4. Vol. 30. No. 205. Dec. 1865. 2 F 



