90 HOW TO SEE WITH THE MICROSCOPE. 



may be required. And by virtue of a nice little con- 

 trivance of Mr. Sidle's, the rotatory movement is very 

 smooth and nearly as central as would be expected from 

 stands of much higher cost. 



When desired, Messrs. Sidle and Poulk furnish a 

 mechanical stage which slips on and oft* in place of the 

 rotary plate above mentioned; this mechanical stage 

 has vertical or horizontal motions to the extent ot 

 three-fourths of an inch. This, however, involves an 

 extra cost of $14. 



To exhaust the list of American makers would be- 

 quite beyond the province of this book. There remain 

 the names of Grunow, McAllister, Pike, Queen, Schraueiv 

 Wales, George Wale, and others. Descriptions of the 

 stands supplied by these various makers have been 

 omitted, partially because the author unfortunately has- 

 little acquaintance with their work, while that of oth- 

 ers which at times he has seen, seem practically to be 

 much the same as those already described, and the- 

 reader would gain nothing by the repetition. 



By way of concluding this chapter, and as supple- 

 mental to what has already been said as to the choice of 

 a stand, the writer would especially insist on the im- 

 portance of a stage thin enough to admit a beam of 

 light at 70, from axis, not that the observer will 

 always work with oblique light, but, when occasion calls 

 for it, the stand should be capable of responding, and, 

 as has been before hinted, in these latter days these 

 kind of calls occur more frequently than was the case in 

 the days of yore. Let the novice especially, then, who 



