SUMMARY OF CURRENT RESEARCHES. 



93 



the stage when a photomicrographic camera is in vise, and a bullseye 

 condenser is included for illuminating opaque objects. 



Watson and Sons' "Mint" Metallurgical Microscope.* — This 

 instrument (fig. 8) is substantially tke same as the " Works " model, 

 previously described in the Journal,! but is not so large nor so massively 

 constructed. The body is of large size, and fitted with rackwork and 

 sliding draw-tubes. The stage is of the raising and lowering type, and 

 has mechanical movements, and partial rotation. The instrument is 

 made with either the horseshoe or tripod form of foot. 



Watson and Sons' Laboratory Dissecting Microscope.^ — The 

 frame of this instrument (fig. 9) is constructed of mahogany ; the sides 

 slope at a convenient angle ; the glass stage, 4| in. square, is removable. 

 The arm, which carries lenses, has a spiral rack-and-pinion adjustment. 

 The mirror is on gimbals. 



Fig. 9. 



Binocular Instruments^ — M. von Rohr's book with the above title 

 treats the subject from three points of view — theoretically, historically, 

 systematically. Part I. (theoretical) discusses the theory of vision 

 (pages 1— ID). Part II. (historical) devotes the following 174 pages to 

 the various types of binocular instruments, and describes in detail their 

 fluctuations in utility during each of the last five decades of the nine- 

 teenth century, the period 1890-1900 being one of marked recovery. 

 Part III. is a very interesting and useful chronological bibliography 

 under numerous heads and sub-heads. 



(2) Eye-pieces and Objectives. 



Photographic Objective containing a Uranium-glass Lens.|| — In 

 connection with the increasing use of colour filters, it has occurred to 



* Watson and Sons' Supplement to Catalogue No. 2, pp. 6-7. 

 t See this Journal, 1904, p. 105. 



X Watson and Sons' Catalogue, 19th edition, 1907-8, p. 71. 

 § Die binokularen Instruments Berlin: Julius Springer (1907) 223 pp. 90 rigs. 

 || Bull. Soc. Franc. Photog., xxiii. (1907) p. 212. See also Zeit. lnstrumentenk., 

 xxvii. (1907) p. 233. 



