344 



CENTBAL SCIENTIFIC CO., CHICAGO, U. 8. A. 



No. 8630. No. 8636 



No. 8640. 



No. 8634. 



CAMERA LUCID A, Abbe's, Continued. 



two concentric screws that the field is free from color to the extreme edge. The light from 

 it is modified by a series of smoked screens of different densities which may be revolved in 

 and out of line between the mirror and the prism. It is made for the standard size micro- 

 scope tubes, now in use by practically all American and European makers. Complete in 



hardwood case $20.00 



8616. CAMERA LUCIDA, same as No. 8614, with the exception that the prism is permanently cen- 

 tered at the factory and that there is no means for modifying the light from the ocular. 

 The prism is the same size and mounted in a similar way. There are no loose parts to get 

 out of place when the prism is moved in and out of the optical center. Complete in hard- 

 wood case 12.00 



8630. EYEPIECES, Huyghenian. In arranging the focal distance of the Spencer eyepieces, the 

 method has now been adopted of marking them with figures that indicate in each case how 

 many times the eye-piece enlarges the objective image, projected the distance of distinct vi- 

 sion (250 mm or* 10 inches). For example, the 4x eyepiece magnifies the objective image four 

 times, and the magnification of the 8x eyepiece will be twice as great under similar condi- 

 tions. A lOx ocular now takes the place of the old 8x and a 5x takes the place of the 4x, 

 the old designation being based on the magnifications of the image projected the distance of 

 the optical tube length, 160 mm. The eyepieces are made to fit the standard tube of the 

 Koyal Microscopical Society. 



No A 



Magnifying power, diameters 4 



Equivalent focus, mm 62.5 



Equivalent focus, inches 2ty 



Each 1.75 



8634. EYEPIECE, Micrometer, with movable scale 5 mm in length, divided into 



The graduated drum, divided into 100 divisions, moves the scale % mm for each revolution, 

 thus permitting readings to be made to }4oo nim - This instrument has a decided advantage 

 over the filar micrometer in that it is not necessary to move the cross hairs the entire length 



of the object. Complete with case 30.00 



8636. EYEPIECES, Micrometer, with fixed scale, providing a convenient method of using the micro- 

 meter scale. The eye lens is mounted in an adjustable sleeve permitting the scale to be 

 brought into exact focus. Scale graduated to 5 mm in I/JOQ mm divisions. 



No A 



Magnifying power, diameters 6 



Each 5.00 



8640. ILLUMINATOR, Dark Pield, for use on any microscope. The condenser is mounted in a solid 

 piece of brass with slots at the end for the stage clips of the microscope. It permits the use 

 of slides on the top surface. The top surface of the condenser is provided with a little ring 

 by which it may be carefully centered. Direct sunlight may be used. Fairly good results 

 may be obtained by using a Welsbach light, but the best source of light is the electric arc 

 light. No. 8682 Arc Light is especially constructed for such work. Complete in neat case, 



including special diaphragm for 1.8 mm oil immersion objectives 10.00 



ARC LAMP for use with No. 8640, see No. 8682. 



B 

 9 



50 



2 



1.75 



C 

 (i 

 40 



1% 

 1.75 



ID 



8 

 30 



1% 

 1.75 



E 

 1(1 

 25 

 1 

 1.75 



F 

 12 

 20 



A I 



1.75 



mm divisions. 



B 



10 

 5.00 



