104 NEW YORK STATE MUSEUM 



As a temporary makeshift to enable us to see our plates as 

 solids we will use the ordinary Holmes stereoscope in one of the 

 following ways. 



Let the observer seat himself before a table arranged to let a good 

 light reach the page from the left side. In front and about ten inches 

 back from the edge of the table place two or three moderately 

 heavy books. Slide the transverse card carrier off the end of the 

 rail of the stereoscope and place this end against the lower edge of 

 the bottom volume. By now placing the forehead against the hood 

 and using a gentle pressure it is easy to hold the instru- 

 ment at an angle of about forty-five degrees and at the same time 

 look through the lenses. Both hands are free to bring any stere- 

 ogram into proper position and focus. The line separating the 

 two views must be kept near the center of the rail and the lower 

 edge of the stereogram kept parallel with the horizontal edges of 

 the lenses. 



This end may also be attained by placing the stereogram with its 

 lower edge close to the edge of the table and holding it as nearly 

 flat as possible with proper weights. Then hold the rail of the 

 stereoscope vertically against the edge of the table and move up 

 or down to focus. 



For a quickly made but more permanent device, procure two 

 pieces of board, one lo inches x 12 inches x ^ inch and the other 

 2 inches x i inch x | inch. Fasten the smaller piece under the 

 middle of one of the 10 inch edges, keeping the two |- inch faces 

 flush with each other. A simple clamp will hold the rail of the 

 stereoscope against this ij inch face. Two or more elastic bands 

 around the board will hold the volume to the stage and both" 

 hands may be left free for other work. 



Still more desirable would be a large inclined stage with spring 

 clips and a stereoscope body that could be focused by means of 

 a rack and pinion as in a binocular microscope. A cheap and 

 convenient form could be modified after Brewsters " box " stereo- 

 scope in which the loaded base of the instrument should rest di- 

 rectly on the printed page. 



If the reader will seek through one or another of the 

 means here suggested to view these stereograms serially and in 



