Niepce (says Mr. Hunt) pursued a physical investigation of the curious change, and found that all bodies were influenced by this principle radiated from the sun. Daguerre[14] produced effects from the solar pencil which no artist could approach; and Talbot and others extended the application. Herschel took up the inquiry; and he, with his usual power of inductive search and of philosophical deduction, presented the world with a class of discoveries which showed how vast a field of investigation was opening for the younger races of mankind. The first attempts in photography, which were made at the instigation of M. Arago, by order of the French Government, to copy the Egyptian tombs and temples and the remains of the Aztecs in Central America, were failures. Although the photographers employed succeeded to admiration, in Paris, in producing pictures in a few minutes, they found often that an exposure of an hour was insufficient under the bright and glowing illumination of a southern sky. THE BEST SKY FOR PHOTOGRAPHY. Contrary to all preconceived ideas, experience proves that the brighter the sky that shines above the camera the more tardy the action within it. Italy and Malta do their work slower than Paris. Under the brilliant light of a Mexican sun, half an hour is required to produce effects which in England would occupy but a minute. In the burning atmosphere of India, though photographical the year round, the process is comparatively slow and difficult to manage; while in the clear, beautiful, and moreover cool, light of the higher Alps of Europe, it has been proved that the production of a picture requires many more minutes, even with the most sensitive preparations, than in the murky atmosphere of London. Upon the whole, the temperate skies of this country may be pronounced favourable to photographic action; a fact for which the prevailing characteristic of our climate may partially account, humidity being an indispensable condition for the working state both of paper and chemicals.--_Quarterly Review_, No. 202. PHOTOGRAPHIC EFFECTS OF LIGHTNING. The following authenticated instances of this singular phenomenon have been communicated to the Royal Society by Andrés Poey, Director of the Observatory at Havana: Benjamin Franklin, in 1786, stated that about twenty years previous, a man who was standing opposite a tree that had just been struck by “a thunderbolt” had on his breast an exact representation of that tree. In the New-York _Journal of Commerce_, August 26th, 1853, it is related that “a little girl was standing at a window, before which was a young maple-tree; after a brilliant flash of lightning, a complete image of the tree was found imprinted on her body.”