158 



INDEX 



Camera dimensions in low-power photo-micro- 

 graphy, 19, 25 

 Centering auxiliary condenser, 105, 138 

 Collodion slides, dry and wet, how to make, &c., 39 

 Condenser, arrangements under, for introducing 

 various coloured glasses, 102 



arrangements for reducing its aperture, 102 



auxiliary, mount by author, its position, 104 



auxiliary, arrangement by author, 104 



auxiliary, by Watson, 104 



by Beck, 98, loi 



by Conrady, 98, loi, 138 



Powell & Lealand, apochromatic N. A. i"o, 97 



by Powell & Lealand, 97, 100, 138 



by Watson, 98 



by Zeiss, 97, 102 



definition in, 99 



for low-power photc-micrography, its uses, 1 5 



for use with i-inch, 119 



for use with half -inch, 126 



for use with high-powers, 135 e« seq. 



how to centre, 102, 103, 138 



leading points concerning, 96 



position of the rays coming from in low -power 



work, 15 

 spherical aberration of, 97 

 substage, 92 



substage Abbe chromatic, 92 

 Cone, aplanatic, 97 



aplanatic, what is meant by the term, 97^ 

 98, 99 



from over-corrected lens, 97 

 from under-corvecie(\, 97 

 from Mwcorrected lens, 97 



of condenser, how to ascertain size of aplanatic 

 cone, 98 



of light effect of bad correction, 99 

 of hght given by the substage condenser, 92 

 Conrady, his formula for ascertaing the N. A. of 

 dry objectives, 90 

 condensers, 98, loi, 138 

 objectives, 78 

 Contrast glasses and screens, their utihty discussed, 

 145 



contrast screens how made, 145, 146 

 Coscinodiscus asteromphalus secondary markings, 



how to photograph, 137 

 Cover-glass adjustment, 84, 85 

 Covering.power in lenses, 18 



Critical angle, 83 



image, 98, 103 



"light," 98, 103, 130 



photography, i, 109, 134 

 Culture tubes, photography of, 26 

 Cylinders for holding compressed gas 8, 



danger of using those made by inferior manu- 

 factures of bad steel, 8 



D 



Dallmeyer's rectilinear for low-power photo- 

 micrography, 18 

 Dangers of using cylinders of bad steel, 8 

 Dark ground illumination of objects placed on 

 microscope, 112, 132 



room, testing of, 33 

 Davis diaphragm, use of, with the one-inch, 121 



diaphragm, use of, with the half-inch, 127 

 Depth of focus, 86, 129 

 Developer, formula for negatives, 33 



for wet collodion plates, 40 



for lantern plates, 33, 37 



for dry collodion plates, 33, 39 

 Developing bromide enlargements, 35 

 Development, medium-power photo-micrography, 

 122 



of negatives for low-power photo-micrography, 

 32 



treatment of over-exposure, 122 

 of negatives forhigh-powerphoto-micrography, 

 142 



Diaphragm used with " Planar " and Dallmeyer 

 lenses in low-power photo-micrography, 22 

 Diatoms, mounters of, 130 



Direct light for illuminating objects placed on 



microscope, 110 

 Double oblique light, 113 

 Drying negatives, 35 



E 



Edinburgh model microscope for photo-micro- 

 graphy, 66 



Edwards's "Antihalo" and isochromatic plates, 

 their use of in photo- micrography, 19, 20 

 "snap-shot" plate, occasional use of, 139, 

 142 



