488 



SUMMARY OF CURRENT RESEARCHES RELATING TO 



ground focusing screen provided with rectangular micr>)metric divisions ; 

 in eacli of whicli appears one of the twenty images. At D is hinged a 

 small strongly magnifying Microscope by which the images may be 

 focused, the whole being adjusted by a screw clamp at E. At about a 

 quarter of the length of the claamber from B is a plate F with an opening 

 closed by the sliding screen G held by a counterweight, so that when 

 drawn aside it immediately returns, admitting an instantaneous flash of 



Fio. 145. 



light. The sensitive plate C receives twenty images at a time and in this 

 way, by five consecutive exposures on adjacent jjarts, a hundred minute 

 photographs may with ease be taken upon a plate measuring 2 cm. by 

 15 cm. A lateral opening closed by the sliding door X allows the 

 operator's hand to be passed into the box. 



Bousfield's 'Guide to the Science of Photo -micrography.'* — To those 

 who for many years have watched the progress of pliotomicrography, and 

 who must have often seen brought forward, as novelties and advantages, 

 devices that were adopted years since, it will be very satisfactory to find in 

 Dr. E. C. Bousfield's brochure not only a trustworthy guide to the gelatino- 

 bromide process which has been selected, but a real advance in the endeavour 

 to set the principles of the most difiicult portion of the subject upon a 

 scientific basis. 



The rapid spread of photomicrography amongst microscopists is, doubt- 

 less, largely due to the facilities furnished by the use of the dry gelatino- 

 bromide plates, and their sensitiveness to the rays from ordinary artificial 



* Boiisfield, E. C, 'A Guide to the Science of Photo-micrography; containiug 

 Exposure-tables and rules for working,' G9 pp, and Table, 8vo, London, 1887. 



