Licence: Public Domain Mark
Credit: Account of the organ of hearing in fish / By John Hunter. Source: Wellcome Collection.
10/14 page 384
Licence: Public Domain Mark
Credit: Account of the organ of hearing in fish / By John Hunter. Source: Wellcome Collection.
![[ 3§4 ] XXIV. Account of a new Electrometer. By Mr. Abraham Brook ; communicated by Sir Jofeph Banks, Bart. P. R. S. % Read May 30, 1782. AAAAN, fig. 1. reprefents the electrometer in full (ize and proportion, (landing on a table, or the like. The foot B is a iquare piece of board, 9$ inches each way, reding on three pins C, C, c, feen at the under fide of the foot. C, C, with the broad heads, are fcrews to fet the inftrument upright withal. D is a folid piece of glafs, which fupports and infulates the inftrument from the place on which it (lands. The arms Gi and g9 with the ball F, turn round on the wire H (which is folid brafs, as may be alfo the arm gf and, when in ufe, are put near at a right angle with G2 and H, being turned to the off fide fo as to be as much as poftible out of each other’s atmo- fpheres or the atmofphere of a jar, battery, prime conductor, &c. The arms Gi and G2 are hollow tubes of copper, not fo heavy as wires. The balls Ii, I2, are made of copper, and hollow, fo as to be as light as poftible. K reprefents a kind of face or dial plate to the inftrument with its index, which is car- ried once round by the motion of the arm G2 with its ball 12 moving through a quarter, or 90 degrees, of a circle ; this motion is given to it by the repul five power of the charge, &c. of electricity between the two balls I2 and L. The ends of the index from its center are of different lengths. The longed ^nd reaches to a graduated circle, divided into 90 equal parts, anfwering,](https://iiif.wellcomecollection.org/image/b29007094_0010.jp2/full/800%2C/0/default.jpg)
