10. _Light has been supposed to produce a certain degree of influence on the_ PROPAGATION OF SOUND?--M. Parolette, in a long paper in the ‘Journal de Physique,’ vol. 68, which is copied into ‘Nicholson’s Philosophical Journal,’ vol. 25, pp. 28-39,--has offered a variety of remarks, and detailed a number of experiments on this subject. The author states the following circumstances as having suggested the connection between light and sound. ‘In 1803, I lived in Paris, and being accustomed to rise before day to finish a work on which I had long been employed, I found myself frequently disturbed by the sound of carriages, as my windows looked into one of the most frequented streets in that city. This circumstance which disturbed me in my studies every morning, led me to remark, that the appearance of day-break peculiarly affected the propagation of the sound: from dull and deep, which it was before day, it seemed to me to acquire a more sonorous sharpness in the period that succeeded the dissipation of darkness. The rolling of the wheels seemed to announce the friction of some substances grown more elastic; and my ear on attending to it perceived this difference diminish, in proportion as the sound of wheels was confounded with those excited by the tumult of objects quitting their nocturnal silence. Struck with this observation, I attempted to discover whether any particular causes had deceived my ears. I rose several times before day for this purpose alone, and was every time confirmed in my suspicion, that light must have a peculiar influence on the propagation of sound. This variation, however, in the manner in which the air gave sounds might be the effect of the agitation of the atmosphere produced by the rarefaction the presence of the sun occasioned; but the situation of my windows, and the usual direction of the morning breeze, militated against this argument.’