306 



THE USE OF THE MICROSCOPE 



Condenser, dark-field, for objects in 

 water, 94 



testing, 173 



training in the use of, 3 

 dry, 86 



achromatic, 32 



corrected by unscrewing, 252 

 focal differences, 88 



test for correction, 249 

 focusing, 32 

 history of, 201 

 immersion, 32 

 immersion oil with, 86 

 iris, adjustment of, 2 

 kinds of, 80 

 lamp distance, 251 

 lenses for correcting, 90 

 Leuchtbild, dark field with, 95, 



202, 254 

 marking apertures of, 267 

 oil-immersion, corrected for water- 

 immersion, 252 

 over-correction, 89 

 practical points, 97 

 reflecting, 94 

 regulating iris of, 92 

 ring test, 89, 250 

 scale on, 93 

 sleeve, stop for, 154 

 slide thickness, 251 

 stop for dark field, 93 

 suggested, 87 

 summary, 96 

 • testing, 87, 172 

 uncorrected, 81 



aperture of, 83, 201 



disadvantages of, 83 



and ground glass, 252 



illumination, 73 



and large source, 248 



and lens, 251 



and small source, 91 



superfluous, 204 

 under-correction, 89, 91 

 upper lens, 87 

 use of, 89 



water-immersion, 87, 106 

 Conrady, circular source, 69 

 diatom test, 122 



Conrady, dry objectives over 0.85 

 N.A., 128 

 large cones, 203, 212 

 in Spitta's book on the micro- 

 scope, 210 

 Convergence of tubes, 37 

 Corning Glass Co., daylight glass, 76 

 Correction by drawtube, 142 

 Correction collar, for dry objective, 

 112 

 use of, 260 

 Cover-glass, care of, 178 

 cleaning, 178 

 disuse of, 112 

 measuring, 258 

 mounting on, 102 

 practical points, 114 

 problem, 2, 110 

 final solution, 115 

 summary, 113 

 proper thickness, finding, 259 

 remedies for wrong thickness, 111 

 thick, 63, 262 

 thickness, 110, 261 

 working without, 63 

 Czapski, book on optical instru- 

 ments, 211 

 twin-objective binocular, 43 



D 



Dallinger, plane mirror, 137 

 reflecting prism, 138 

 revision of Carpenter on the 

 microscope, 210 

 Dammar, for sealing, 177 

 Dark field, with achromatic con- 

 denser, 253 

 advantages of, 96 

 with bicentric condenser, 254 

 with cardioid condenser, 254 

 with Cassegrain condenser, 254 

 with center stop, 93 

 complementary colors in, 95 

 condensers, 93 



for objects in balsam, 95 



in water, 94 

 resolution of, 203 

 testing, 173 

 disadvantages of, 96 



