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SCIENCE-GOSSIP. 



CONDUCTED BY J. H. COOKE, F.L.S., F.G.S. 



To whom Notes, Articles and material relating to Microscopy, 

 and intended for Science-Gossip, are, in the first instance, 

 to be sent, addressed "J. H. Cooke, Edlestone, Battenhall 

 Road, Worcester." 



A New Photo-micrography. — Seven years ago 

 Dr. Lenal described in a leading scientific journal, 

 published in Germany (Zeitschr. f. Wiss. Mikr.), 

 an instrument consisting of a microscope with a 

 second microscope attached to it in place of an 

 eye-piece, by means of which he claims to be able 

 to obtain a much greater magnification of the 

 primal image than had hitherto been secured by 

 any combination of eye-pieces and objectives. Dr. 

 Dallinger, E. M. Nelson, and other eminent 

 British microscopists reviewed Lenal 's method, 

 and pointed out, at the time, that it was fallacious 



objective. By means of his apparatus he has 

 made photo-micrographs of Pleurosigma magnified 

 450 diameters, 1,450 diameters, 6,000 diameters, 

 and 10,000 diameters. By focussing a sixth on a 

 sixth objective he obtained a photograph of a 

 portion of the same object enlarged 360,000 dia- 

 meters. This he considers to be the limit at present 

 obtainable with an ordinary camera in a dark 

 room, and with the usual photographic technique : 

 but, given suitable conditions, he expects, by using 

 a twelfth objective in the first microscope, and a 

 sixth in the second, to obtain a magnification of 

 1,200,000 diameters, which will be equal to an area 

 of 1,440,000,000,000 times the area of the original 

 object. This may sound incredible, but he states 

 that he has already obtained evidence of being 

 able to photograph a magnification of over three 

 million diameters, or over twelve trillion times the 

 area of the object. Expensive objectives are quite 

 unnecessary for this purpose, as low-power lenses 

 are all sufficient to do the very best work. 

 Some idea of the arrangement of Professor Gates's 

 apparatus may be obtained from the accompanying 

 figure. At the extreme left is an arc lamp, next to 

 which are the condensing lenses, then the alum 

 filter with its bellows, and after, the lenses used to 

 render the rays parallel. The revolving diaphragm 

 is placed at the right-hand end of the parallelizing 



ISIFf 1 



Gates' Double Microscope with Arc-lamp, Condensing and Parallelizing Lenses, Alum Filter and Camera. 



to suppose that the working-power of any objec- 

 tive could be increased by subjecting the primal 

 image of an approximately perfect object-glass to 

 examination by a second microscope or other 

 complex combination of lenses. Greater magnifi- 

 cations may be obtained, but such enlargements 

 will simply be those of the" details of the micro- 

 scopic image which has been brought about by 

 diffraction in the first objective, and therefore 

 there cannot by any possibility be a single 

 detail added ; while the details that the accu- 

 rate image does disclose must be blurred and 

 tortured tenfold more than when subjected to the 

 legitimate action of well-constructed eye-pieces. 

 Notwithstanding, however, the scathing criticisms 

 with which Lenal's methods were received, other 

 workers continued experimenting in the same direc- 

 tion, and Professor Elmer Gates now describes in 

 the pages of the current issue of the " American 

 Microscopical Journal "a perfected form of Lenal's 

 apparatus. By placing two microscopes end to 

 end, the first fitted with a one-sixth objective, and 

 the second with a half-inch objective and a one- 

 inch ocular, Gates claims that he can get much 

 better definition and detail than can possibly 

 be obtained under any conditions by the use 

 •of either a one-sixteenth or a one twenty-fifth 



lenses. Between the bellows of the filter-cell and 

 the parallelizing lenses there is a screen holder, in 

 which is placed coloured gelatine films to screen 

 out such rays as may not be desirable. Beyond 

 the revolving diaphragm the light next enters the 

 sub-stage Abbe condenser, and thence through the 

 object to the two microscopes and the camera. 

 The arc lamp used is of about 2,000 candle-power. 



The Malaria Microbe. — The recent researches 

 of Surgeon Ross, of the Army Medical Corps, 

 have proved that malaria can be acquired from a 

 mosquito bite, and that the malaria microbe is 

 one which, as a rule, prefers insects as a medium 

 for its propagation rather than man. Particular 

 species of malaria parasites even demand parti- 

 cular species of mosquitoes, a fact that partly 

 explains the apparent vagaries in the distribution 

 of varieties of malaria. When all is known 

 Europeans may be able to live in climates now 

 made deadly by this pest. 



" Illustrated Annual of Microscopy.'' — One 

 of the principal desiderata of microscopists for years 

 past has been an " annual " in which details of the 

 progress made in the various departments of 

 research might be recorded, and the newest devices 

 in apparatus and methods illustrated and described. 



