THE HISTORY AND DEVELOPMENT OF THE MICKOSCOPE 



All the fittings are sprung and have adjusting screws to compen- 

 sate for wear. 



Coming now to Third-class microscopes, we note that the dis- 

 tinguished American firm, Bausch and Lomb, make a very useful 

 instrument which must be placed in this class. It is intended as 



FIG. 178. Bausch and Lomb's C.A.S. microscope ils'.'i i. 



a high-class laboratory instrument for advanced work and for use 

 in independent researches. It is designated by the firm as the C.A.S. 

 It lias a large stage, but in our judgment this would be greatly im- 

 proved by being furnished with the horseshoe opening so valu- 

 able for hand focussing as a preliminary in the use of high powers 

 and immersion lenses. Of course the mechanical stage of the 



