INDEX 



361 



Newton's mixed-gas jet, 4 

 Nikko paper, mounting of, 44 



polishing of, 43 



prints on, 42 

 Note on aperture of condensers, 89 



of " exclamation " in Podura scale, 139 

 Nottingham hard limes, 1 1 



Numerical aperture, how ascertained by Oonrady's 

 method, 90 

 how obtained by use of apertometer, 88, 89 

 N. A. discussed, 85 

 of objectives, 86 



apertures, how compared with high, 87 



0 



Objectives, achromatic, visual and photographic, 

 78-79 

 apochromatic, 80 

 changers, 73 



changers, care in use of, 74 

 dry and immersion, 81 



immersion, why they give so much more licht, 



83, 84 

 selection of, 77 

 Objections to using inferior oxygen, 137 

 Oblique light, for illuminating objects placed on 

 microscope, no 

 " double," 1 1 3 



misinterpretation of results obtained thereby, 

 94 



use of, 132 



Zeiss method of obtaining, 1 1 1 

 Oculars, 90 



Oil light in photo-micrography, 2 

 Opaque objects, their illumination for the micro- 

 scope, 113, 132 



P 



Parabolic reflector, use of, with low powers, 

 133 



Paraboloid, 112 



Pathological specimens, the photography of, 32 

 " Penetrating-power " of different apochromatics, 

 table of, 129 



Periodic structures, how to determine their rate 

 per inch, &c., in specimen when its ampli- 

 fication is known, 149 

 how to use a millimetre measure for ascer- 

 taining the space in which a number of 

 periodic structures can be counted to the 

 inch, 149 



Petzval lenses, use of, in low-power work, 17 

 Photograph, medium-power work, how to take, 

 119 



Photographic apparatus for enlargement on bro- 

 mide, 29 



for low applied power work, 14, 24, 37 

 lenses of ordinary type, to photo-micrograph 

 with, 17 

 Photographs of bacteria, 1 43 

 Photo-micrography, backing of plates, 20 

 critical work, i, 109, 134 

 how to avoid tremulations of floor, 47 

 introdviction, i 



medium-power apparatus, 48 

 the microscopes used for, 59 

 medium-power work, i, 47, 109 

 table — 



designed by author, 54 



by Baker, 49 



by Beck, 49 



by Swift, 51 



by Ross, 52 



by Watson, 52 



by Zeiss, 52 



Photo-micrograph, vertical apparatus by Watson, 

 after Yan Heurck, 56 



by Zeiss, 57 

 " Planar " lenses for low power work, 18 

 Pleurosigma angulatum, how to photograph, 138 



mathematical inquiry concerning details of 

 image, 141 

 Podura scale, how to photograph, 139 

 Polarised light exposure, 133 



how to obtain, 114, 133 



table of substances which show well, 133 

 Polyxenus lagurus, how to photograph, 134 

 Positives, printing of, on paper, 41 

 Powell &L Lealand's apochromatic 1-40 condenser, 

 100 



lenses, 135 



microscope for photography, 62 

 Prints on albumen paper 41; 



X 



