150 REVIEWS. 



Le Temps de Pose. Par A. de la Baurae Pluvinel. Crown 

 8vo, pp. viii. — 121. (Paris : Gauthier-Villars et Fils. 1890.) 



This is an elaborate mathematical treatise on the theory and practice of the 

 exposure of the sensitive medimn — too elaborate, we fear, for the general run 

 of operators. We are sadly too apt to go by rule of thumb and to regulate 

 the time of an exposure by our estimate of the photographic value of the light 

 and the known power of the lenses we are working with. But if we go with 

 Mons. Pluvinel we shall require a thorough mathematical education. We have 

 no doubt that the conclusions arrived at are sound, but the method of arriving 

 at them seems circuitous. 



La Photographie a la Lumiere. Par Le Dr. J. M. Eder. 



Crown 8vo, pp. vi. — 63. (Paris : Gauthier-Villars et Fils. 1890.) 



The process of obtaining good results by means of the magnesium light is 

 well set forth in this little treatise, and the various forms of magnesium lamps, 

 with their several advantages and disadvantages, are well described and illus- 

 trated by a series of very good and clear diagrams. 



Great Thoughts. (London: A. H. Hall, 132 Fleet St.) 



This magazine is published in weekly numbers and in monthly parts. The 

 parts dated February and March are now before us. They contains extracts 

 fVom the best writers of all ages, Portraits and Memoirs of celebrated 

 personages of our own and earlier times, a story of much interest by Dr. Joseph 

 Parker, Poetry, etc. etc. 



Research. Edited by A. Norman Tate, F.I.C., F.C.S., 

 F.G.S., F.R.M.S., etc. (London : E. W. Allen.) Monthly, price 3d. Is 

 a monthly illustrated Journal of Science. 



One of the chief features of this Journal is the monthly publication of the 

 portrait of one of our eminent Scientists. The March number contains that 

 of Prof. John W. Judd, F. R.S., F-.G.S., etc. Other papers of interest are : 

 Physics of the Earth's Crust, Vaucheria and a Parasitic Rotiferon, The 

 Evolution of Man, Scientific Research in Yorkshire, Dust in the Air, and 

 many others. One of the engravings exhiljits a Russian giantess, a young 

 lady of only 12 years of age, who has already attained the height of six feet 

 eight inches, a height which she promises considerably to exceed. 



Life Lore. Edited and published by W. Mawer, Essex 

 Street, Strand. Price 4d. monthly. 



In every sense a magazine of Natural History. Its articles are well 

 written, and the illustrations are many and good. In February was commenced 

 " A Course of Vegetable Physiology." A series of interesting papers 

 addressed to young people is a special feature of this magazine. 



Knowledge. Edited by A. Cowyer Ranyard. Published by 

 W. H. Allen and Co. 6d. monthly. 



An illustrated magazine of Science, simply worded, and exactly described ; 

 affords a large amount of useful and valuable information monthly. 



Illustrations. Conducted by Francis Geo. Heath. (Office : 

 I St. Swithin's Lane.) Price 3d. monthly. — This is a magazine of Amusement : 

 Art, Biography, Economy, Invention, Literature, and Science. We can 

 confidently recommend "Illustrations" to our readers. 



