WONDERS OF PHOTOGRAPHY. 607 
made cloud-camera, which acts automatically, has just been commenced. The 
form and disposition of clouds have always been regarded as an index to the 
weather, and weather records compared with cloud-photographs will doubtless 
afford valuable information and assistance in weather prognostications. 
To the geographer and ordnance surveyor the camera will soon be regarded 
as an indispensable part of their outfit. The tedious operations of making 
sketches, of a district will be obviated, and perfect pictures with hardly a chance 
of error will easily be obtained. 
To the medical man too, and the chemist, photography is found to be a 
valuable assistant. At the Glasgow Medical School the successive stages ol surgi- 
cal operations, sections of tumors and diseased structures, and in fact any re- 
markable forms of disease, are photographed, and the prints shown to medical 
students and distributed among the profession to assist in the diagnosis of rare 
forms of disease. Dr. Lennox Brown and Mr. Cadett have recently got some 
wonderful photos of the interior of the larynx. By an adjustment of mirrors in 
the mouth and the electric light to illuminate the throat, they obtained perfect 
pictures of the various positions of the laryngeal muscles during the act of singing ; 
and we may expect that such photos will be found of great value, not only in 
the teaching of classes of medical students, but as aids to the study of the me- 
chanism of the voice. Further, Dr. Koch has recently got some remarkable 
photographs of bacteria and bacilli by the aid of the camera and microscope; and 
here, again, such pictures may be made of incalculable value in disseminating a 
knowledge of these minute but most formidable enemies of mankind. 
In medical jurisprudence, when' it is stated that the crystals formed by the 
one-thousandth of a grain of arsenic have been successfully photographed, it 
will easily be seen that, in cases of poisoning, photography may prove a very 
valuable assistant in the detection of crime. A novel use of the art is now being 
made in the Municipal Laboratory of Chemistry at Paris ; photographs of choco- 
late, tea, coffee, pepper, milk, cheese, etc., as seen through the microscope, are 
taken and distributed; and, by comparing samples of such articles with photos 
of the pure article, an easy method is afforded, even to non-professionals, of detect- 
ing adulteration. 
Photography is utilized by the microscopist in other directions. Accurate 
views have been secured of the most minute objects, just as they appear under 
the most powerful microscope. Photos of minute diatoms, polycystina, infusoria 
in motion, bacilli, and trichini have recently been obtained by the writer of this 
article under a power of looo diameters. The cilia of animalculse, blood cor- 
puscles, the microscopic structure of bone and tissue are shown most distinctly, 
and details are seen easily which often escape the eye in microscopic examina- 
tions. A large photo, six inches in length, of a small fly's toiigue measuring 
about one- seventieth of an inch, shows the hairs and various markings with re- 
markable clearness. A simple calculation shows this photograph to cover an 
area 176,000 times as large as the original object. Again, views of the internal 
structure of wood show conclusively whether the wood is weak or strong; in 
