NOTES:

1. Transactions of the Society of Arts, 1819, p. 116.

2. The contrivance is due to Mr Hencky, of High Holborn, in whose establishment it is in constant use.

3. About seven or eight years since, without being aware of Sir David Brewster's proposal. I adapted a barometer, as a pendulum, to the works of a common eight day clock: it remained in my library for several months, but I have mislaid the observations which were made.

4. Memoires de l'Academie des Sciences de Petersburgh, 6e serie, tom. i. p. 4.