On Stereomierograpliy . By G. P. Girdwood. 



13 



two points in the circumference 2h in. apart, and joining those points 

 by radii to the centre ; the two radii will represent the axes of the 

 two eyes, and the line between them the distance between the centres 

 of the two pupils. And now, if a Microscope slide be so placed as 

 to form a normal with the radius representing the axis of the left eye, 

 a picture will be given representing the object as seen by the right eye, 

 and then, if sloped in the opposite direction without moving the central 

 object or part thereof, it will, when viewed in the course of the second 

 radius, present a picture as seen by the left eye. 



Now, if a Microscope slide with the objects upon it be moved on a 

 centre or point of convergence so as to make the surface of the slide 

 a plane normal to the line representing the axis of the left eye, it 



Fig. 14. 



The apparatus is adjusted upon the stage of the Microscope so that the 

 centre is in the optic axis of the instrument. The object is placed on 

 the tilting table by spring pressure (springs not shown). The level of the 

 object is the same as the axis upon which the tilting table swings, so that 

 the motion of the table does not alter the position of the object except as 

 to inclination. The object may be moved about till the required portion 

 to be photographed is found, the tilting table being rigidly attached to the 

 Microscope; and the inclination of the table is set by means of the two 

 screws at its ends. 



right 



will give a picture as seen by the right eye ; and shows from the 

 what is hidden behind the central object of the picture ; and if it be 

 inclined so as to form a normal with the line representing the axis of 

 the right eye, the picture seen in the Microscope will be the picture 

 as seen by the left eye, and shows objects behind the central object 

 as seen from the left side. If two pictures be taken thus, and these 

 two pictures printed and mounted, they will give most beautifully the 

 stereoscopic effect, and will show at once in the stereoscope the third 

 dimension and the different planes in which the objects are seen at the 

 time of observation. 



