Photometer

an apparatus for mea- suring the intensity of light, and likewise the transparency of the medium through which it pa es. Instruments for these purposes have been invented by M. de Sau ure, Count Rum- ford, Mr. Leslie, . Profe or Leslie’s is indeed the simplest instrument of the kind of which we.have any where met with a. descrip- ‘tion; but it measures only the momentary intensities of light; and he who wishes to be informed of its construction, will find that information in the third volume of Nicholson’s Philosophical Journal, 4to, or in the pro ah interesting work on the nature of jeat