ZOOLOGY AXD BOTANY, MICROSCOPY, ETC. 709 



of the cross bar, opposite that which carries the pulleys, and by means 

 of these the fine adjustment may be turned from a distance. 



A fiat opaque object, such as a chick blastoderm, may be brought 

 into the focal plane of the objective by the following device (figs. 138 

 and 139) : — To the centre of a brass plate of the size and form of the 

 Microscope stage is soldered a flat brass ring 40 mm. in diameter and 

 9 to 10 mm. high, thus forming a shallow pan in the centre of the 

 brass plate ; to the centre of one face of a small brass disc 30 mm. in 

 diameter, a brass ball of about 6 mm. in diameter is attached by a stem 

 2 mm. long; this ball is received into a socket between the lower face 

 of the brass pan and a small brass disc screwed to it, and this socket 

 is packed with oiled leather ; the small metal plate then forms a sort of 

 false adjustable bottom within the pan, which is filled with alcohol and 

 placed on the Microscope stage ; the specimen is then place 1 on the 

 false bottom which is tilted until the specimen lies as nearly as possible 

 in the focal plane of the objective. The brass plate may be provided 

 with holes by means of which it may be attached by pins inserted 

 into the clip-holes of the Microscope stage. 



(4) Photomicrography. 



Bagshaw, W. — Elementary Photomicrography. London, 1902, 70 pp. and 6 pl ft 



Marktanner-Tukneketscher, G. — Wichtigere Fortschritte auf dem Gebiete 

 der Mikrophotographie und des Projektionswesens. 



[Gives a very complete resume of international progress in photomicrography.] 

 Jahrb.f. Photographie unci lieproductionstevknik fur das Jahr 1902, Halle; 



also in pamphlet form, 21 pp. and 5 figs. 



(5) Microscopical Optics and Manipulation. 



Kraft, C. — Etudes experimentales sur Techelle des couleurs d'intsrferance. 



[The author describes the mapping out of the colours of various spectra in 

 connection with the corresponding wave-lengths.] 



Bull. Int. Acad. Sci. Cracovie, No. 5 (1902) pp. 310-53 (4 pis.). 



t6) Miscellaneous. 



Chambers and Inskeep's Improved Ophthalmometer.* — This in- 

 strument, for measuring the curvature of the cornea, possesses, as its 

 special characteristics, stationary and luminous mires and adjustable 

 prisms. These features give it, say its inventors, a distinct superiority 

 over other forms of ophthalmometer. 



Fig. 140 gives a rear side view of the instrument, and shows the 

 adjustments for focussing, for perpendicular adjustment, and for moving 

 the prisms. Fig. 141 presents the stationary mires and head-rest. The 

 construction will be understood from fig. 142. which is a vertical section 

 of the instrument, d is the outer tubo mounted to rotate in sleeve or 

 collar s, supported by standard t, the standard being swivelled in 

 tubular support g ; h is a diaphragm ; 10 is the eye-piece, with suit- 

 able lenses a and b ; n is a stationary disc borne on collar s, graduated 

 to indicate angles of meridional deviation of plane of mires; i is a 



* Chambers, Tnskeep & Co.'s Special Catalogue. 



