ZOOLOGY A.ND BOTANY, MICROSCOPY, ETC 103 



(fig. 13). This cap easily fits on to the objective, and surrounds it with 

 an isolating mantle of air. 



For the determination of temperatures at which fluid crystallization 

 and allotropic changes occur, the author considers his apparatus would 

 be eminently suitable. 



Fig. 14 shows the general arrangement with resistance coil. 



(4) Photomicrography. 



Simple Object-holder for Photomicrography : Tables of Magnifi- 

 cations.* — R.Muller describes this apparatus, which he has designed and 

 found very useful. He uses it with the Zeiss horizontal-vertical camera, 

 but slight alterations would adapt it to other Microscopes. The apparatus 

 consists of a board 50 x 50 cm., secured by two lateral boards to the 

 object-stage ; it may be arranged for horizontal or vertical adjustment. 

 In the horizontal position, the surface of the object-bolder lies accurately 

 at the height of the Microscope stage, the Microscope itself being per- 

 pendicular and firmly clamped on the foot-plate. In the vertical position, 

 a hole is cut out of the board for the object-stage of the horizontally- 

 inclined Microscope. Two adjustable laths with clamps serve for holding 

 the objects to be photographed, e.g. culture-dishes, negatives, water- 

 chambers, etc. A special shelf is used for photographing paper pictures. 

 The whole arrangement is ingenious, and the author gives numerous 

 pictorial illustrations of its application, as well as a very complete tabular 

 list of the necessary numerical adjustments. 



Wratten and Wainwright's Photomicrography, f — This handy 

 little book is written in a clear and lucid style, and is intended to be a 

 trustworthy guide to the beginner. Its style is expository, not scientific. 

 Its object is not to discuss possible methods, but to explain the easiest, 

 and, while some of the statements made need qualification, it lias been 

 thought best to do so rather than to perplex the beginner by diffuseness. 

 The work is not intended to replace the regular text-books of the subject, 

 but to supplement them. Some beautiful examples of photomicrography 

 are given in the plates. 



New Photographic Apparatus of the Paris School of Mines.J 

 J. Boyer describes this apparatus, which was devised by H. Ragot, of the 

 G-eological Laboratory of the Sorbonne, for the reproduction of opaque 

 and of transparent objects. It is also intended for photographing micro- 

 scopic objects (fig. 15), but instead of moving the Microscope by means 

 of a rack-and-pinion, focusing is effected by moving the object. The 

 entire apparatus is attached to a rigid beam, and may be used in a hori- 

 zontal or a vertical position. The object-holder rests on a carriage which 

 is movable upon a second and larger carriage. The large carriage is 

 moved rapidly by turning one of the wheels and long rods shown in the 

 photograph, and the smaller carriage is moved slowly, with respect to the 



* Zeitschr. wiss. Mikrosk., xxvii. (1910) pp. 265-71 (11 figs.). 



t Wratten and Wainwright, Ltd., Croydon, 16 pp. (6 pis. and several figs.). 



% Scientific American, ciii. (1910) p. 104 (2 figs.). 



