ON THE USE OF 



instrument figured is one of those exhibited by Messrs. 

 Crouch at the Manchester Exhibition of Science and 

 Art. 



FIG. 3. 



The advantage of the binocular is chiefly in the rest 

 it gives the eyes, which have no unequal and unnatural 

 strain. 



The field of vision is extended, and objects are seen in 

 relief, round, life-like, and distinct. The joints of insects 

 are seen in a wonderful manner, the ball and socket joints 

 and hinge joints, if well prepared, are now perfectly realised; 

 the hairs of plants and animals are seen in their true posi- 

 tion ; suckers, especially those on the foot of Dyticus, 

 present themselves in the erect attitude of life, and Diatoms 



