226 ANNUAL OF SCIENTIFIC DISCOVERY. 



similar pairs arose at a distance from each other. Although I often suc- 

 ceeded in uniting- two or more of these images, yet the effect of this was to 

 place others at a greater distance ; and I had no hesitation in coming to the 

 conclusion, that the lenses of the object-glass which produced these images 

 were imperfectly centered. Having had occasion to sce'atthe Paris Exposi- 

 tion, and more recently at Florence, the superior performance of Professor 

 ,Amici's microscopes, I cannot omit the present opportunity of urging phi- 

 losophers and opticians, as I have often done, to correct the colors of the 

 secondary spectrum by fluids or solids of different dispersive powers. 

 Professor Amici has done this. In his object-glasses, numbers one and two, 

 of low powers, he employs four different refractive and dispersive substances. 

 In his powers numbers three, four and five, he employs five such substances ; 

 and in his highest power, number six, he employs six. In recommending, 

 as I have often had occasion to do, the employment of diamond and other 

 gems in the construction of compound as well as simple microscopes, I 

 have been met with the objection that they are too expensive for such a pur- 

 pose, and they certainly are for instruments intended merely to instruct and 

 amuse ; but if we desire to make great discoveries, to unfold secrets yet hid 

 in the cells of plants and animals, we must not grudge even a diamond to 

 reveal them. If Mr. Cooper and Sir James South have given a couple of 

 thousand pounds for a refracting telescope, in order to study what have been 

 mis-called "dots" and "lumps" of light on the sky; and if Lord Rosse 

 has expended far greater sums on a reflecting telescope for analyzing what 

 has been called " sparks of mud and vapor " encumbering the azure purity 

 of the heavens, why should not other philosophers open their purse, if they 

 have one, and other noblemen sacrifice some of their household jewels to 

 resolve the microscopic structures of our own real world ; to unravel mys- 

 teries most interesting to man ; and disclose secrets which the Almighty 

 must have intended that we should know ? 



ON THE PHOTOGRAPHIC EFFECTS OF LIGHTNING. 



The following is an abstract of a paper on the above subject recently pre- 

 sented to the Royal Society, Eng., by Andres Poey, director of the observa- 

 tory at Havana. The first, though not the earliest authentic mention of this 

 singular phenomenon was made by Benjamin Franklin, in 1786, who fre- 

 quently 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. A similar case is mentioned by the 

 " Journal of Commerce," New York, on the 2Gth of August, 1853. "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. This is not the first instance of the kind." M. 

 Raspail, in 1855, has also mentioned another instance. He says that a boy 

 having climbed a tree for the purpose of robbing a bird's nest, the tree was 

 struck, and the boy thrown upon the ground ; on his breast the image of the 

 tree, with the bird and nest on one of its branches, appeared very plainly. 



