of the value of three-half pence, will maintain this light in full brilliancy for eight hours. We also think that the light is very applicable to light houses, for which its brilliancy renders it particularly eligible. A large aerometer might be filled in the course of the day by the attendants on the light-house on those rare occasions when there was not wind for working a small wind-mill, with which the light-house, where it is adopted, would of course be supplied ; and the apparatus is altogether so simple, that we consider it quite as secure as the argand-lamp, over which it has great advantage in economy, but infinitely greater in the intensity of its light.

Upon the whole, we consider this to be one of the most important economic and useful discoveries of the time.