560 



SUMMARY OF CURRENT RESEARCHES RELATING TO 



desired point in a vertical direction. The cross-bar also slides through 

 B, so that it can be set (by E) at any point in a horizontal direction. 

 The camera is fixed to one end of the bar. It has an opening on its 

 lower side, to which is attached a piece of tube, into which the eye- 

 piece end of the Microscope passes. To keep out the light, a broad 

 indiarubber band can be passed over the point of junction. 



Seibert and KraflFt's Small Camera Lucida. — This (fig. 98) is but 

 an unimportant variation of the apparatus of Nachet and others, thoiigh 

 somewhat cheaper. Two reflecting plates at a and b are inclosed in 

 a small box, open below, and with an aperture at c. A portion of the 

 reflecting surface is removed at a point d concenti-ic with the optic 

 axis, so that the direct rays, h, from the object are seen through the 

 apertures at d and c at the same time as those, g, from the paper. 

 The camera is supported on the pillar e, and is attached by the ring / 

 to the body-tube. 



Fig. 98. 



Fig. 99. 



Winkel's Small Camera Lucida. — This again (fig. 99) is not 

 distinguishable in principle from Oberhauser's apparatus.* A small 

 right-angled prism P is protected by a ring and attached to a No. 2 

 eye-piece. The prism fastening can be turned on s, and centered by the 

 spring /. It is inclined on its horizontal axis by means of s■^. The 

 prism projects the image of the object upon the drawing-paper inclined 

 at an angle of 45°, the pencil being viewed direct. 



Correction of the Distortions produced by the Camera Lucida. t 

 — The following is a translation, somewhat abridged, of Professor 

 L. Malassez's paper on this subject. It was directed specially to the 



* Cf. this Journal, ii. (1882) p. 680. 



t 'Laboratoire d'Histologie du College de France, Travaux de I'Annee 

 1877-8, public's sous la direction de L. Kanvier, Professeur d'Anatomie 

 generale ' C8vo, Paris, 1879), p. 188. 



