THE MICROSCOPE. 269 
would fit snugly into the upper tube of the microscope, by wind- 
ing a strip of thick, unwrinkled, brown paper, two inches wide, 
around one of the brass cases or objective boxes, pasting it care- 
fully as I rolled it. After letting this dry for an hour or two I 
removed the brass cylinder and made another tube to fit into tube 
No. 1 by winding the paper around a big pill bottle. 
By means of a razor I divided the smaller tube diagonally at 
an angle of 35° 25’, inserting the bottle to prevent it from col- 
lapsing. 
After blackening the tubes, I procured 18 circular (elliptical 
are the best) cover glasses having the same diameter as the larger 
tube, which, after cleaning and polishing very carefully, I placed in 
the large tube so as to be supported at an angle of 35° 25’ by the 
oblique surfaces of the small tube. 
The analyzer is now complete, and if you have succeeded thus 
far, you can proceed to try it. 
Place the analyzer in the tube of the instrument, and, setting 
the polarizing plate at an angle of 54° 35’ with the stage, stand the 
microscope on a table six or eight feet back from a window. 
Tip the body of the instrument up and down, until the light 
reflected from the polarizer passes through the tube, and then 
examine with your lowest power, some very thin slivers of the 
mineral] selenite. 
It will probably be some minutes before you get good results, 
but if all goes well you will see a beautiful mosaic of colours. 
Rotate the part of the microscope containing the analyzer and 
each tint changes to its complementary colour. 
The comparatively small amount of light reflected by the 
polarizer renders the use of high powers impossible. However, 
most of the common polariscopic objects as starch grains, chemical 
crystals, &c., show to good advantage. 
The accompanying diagram shows the analyzer in section, 
together with the two angles necessary in the making of the 
apparatus. 
NEW INVENTIONS. 
A SLIDE CARRIER. 
Mr. B. T. Quimpy of Chicago, has invented a slide carrier 
which is particularly adapted to the Griffith club microscope, but 
