APPENDIX
Electricity
25th October 1768, about five miles south of the line. My machine was made by Ramsden, and worked by a flat plate 8 inches in diameter. The phial used was 6½ inches in height and 5½ in diameter without the neck; the distance between the stopper and the coating, 3 inches, the stopper made of wood and fastened to the glass on the inside by a red cement (probably sealing-wax). The electrometer was divided into thirty parts of 1½ inch as nearly as possible. About nine in the morning the machine was set up, the day being rather cloudy, and the ship going between three and four knots.
When the plate was first turned round the cushions appeared to be damp, adhering to the glass so much that it was with difficulty made to move very slowly, although the cushions were screwed on as tightly as possible. After wiping them very well the plate was made to go round, and in about ten minutes electricity was excited, though but in a small degree; the motion of the ship and the shaking of the table, caused by turning the machine, made the electrometer (which was a very unsteady one) move backwards and forwards visibly, so that it was impossible to ascertain exactly at what distance it discharged the phial, it however was guessed to be about a line when at the greatest distance.
It continued to work in this manner about half an hour, in which time several attempts were made to give a shock, but they succeeded very badly, the shocks being very slight,
