INDEX 



717 



Lantern, square 29 



"spotting" or marking 



19, 201, 216 



standard 202 



standard American 25, 200 



storing 218 



summary 220 



troubles in making 219 



typewritten 215 



unvarnished, ink and pen for 207 



varnishing 205 



Lantern slide carrier for delinea- 



scope 28, 63, 196 



carrier for experiments in 



vision 651-654 



permanent 31-32 



push-through form 23 



ways of making 203 



writing them with a pen . . 204-208 

 Lathe bed type of projection ap- 

 paratus 262, 289 



Latitude and heliostat 160 



Lavasseur, Professor E 673, 685 



Law of magnification and reduc- 

 tion 357,369 



Law of reflection 140, 572-574 



Law of refraction 576 



Lecturer, suggestions to on magic 



lantern exhibition 19 



Lecture rooms 439-454 



Lecture room with gallery 448 



with raised seats 449-451 



screen at side 450-45 1 



transluctent screen 453 



Lehmann, fluid crystals, etc. ... 621 



Leiss, C 138 



Leitz, Ernst, 79, 178, 225, 299, 360, 



362, 363, 364, 

 Lens, aberration, chromatic. . . . 583 



spherical ; . . . 580-586 



how corrected 581 



achromatic 583 



aplanatic 581 



axis of, principal and second- 

 ary 576-579 



center of curvature 577 



center, optic 576-577 



concave, convex and menis- 

 cus 577 



concave to make light cone 



parallel 273,276 



convex to make light cone 

 parallel 274-276 



Lens, crystalline of the eye 657 



change of shape in accom- 

 modation 658 



definition of 576 



dioptry of 229-230 



equivalent focus of 580 



focus of, principal and con- 

 jugate 578-582 



focus, equivalent 580 



holder for trial lenses. .651-654 



meniscus 577 



optic center of 576-577 



principal focus of 578 



principal focus, how found 



579-58o 

 principal and secondary axes 



576-579 



radius of curvature of 577 



secondary and principal axes 



of 576-58o 



support for trial lenses. . .651-654 

 unit of strength (diopter) .... 229 

 Lenses, cylindrical for eye defects 664 

 detecting strain in by polar- 

 zed light 626 



for experiments in vision. 65 1-672 



forms of 577 



position in the triple and in 

 the double lens condenser 



10, 13, 591-592 



Oculists' trial 651 



Leonardo da Vinci 674 



Lettering, drawings 374 



fastening the letters 375 



size for drawings 376 



Letters, a-k on specimen. . . .361, 387 



on tissue paper 375 



white on black ground 375 



Levi Ben Gersen 674 



Light from alternating current 



arc 565 



absorption by lenses and ob- 

 ject v 601-602, 620 



amount from sun 138 



amount with petroleum lamp 125 

 for demonstrations in vision 



652, 670 



from arc, cause of 546 



from arc direct and alter- 

 nating current 554 



of arc dependent on tempera- 

 ture 547 



avoiding stray 380 



in center of condenser face ... 44 



