The Microscope. 113 



ideal cement for general work. I attribute its excellence mainly 

 to a process of atmospheric oxidation which my crude ma- 

 terial had been undergoing for years. The filtering while very 

 thin, through both cotton and thick filtering paper, removed all 

 solids of which benzol is not a solvent. There are many little 

 experiences in microscopy which are never mentioned simply 

 because " Oh, any body would think of doing that ! " During a 

 long microscopical life the writer has suffered divers vexations 

 of spirit from ignorance of a " little thing " in mounting ; so.verjt 

 little, indeed, that it seems as if every one who has made a bal- 

 sam mount must know it; as yet I did not till a month ago. 

 Let us have more of the little things in microscopical work; 

 everybody does know everything. 



TURN TABLES. 



H. M. WHELPLEY. M. D., PH. G., F. R. M. S., 

 PROFESSOR OF MICROSCOPY, ST. LOUIS COLLEGE OF PHARMACY. 



AMONG the mechunical devices employed by a large propor- 

 tion of those who work with the microscope is the turn table. 

 In referring to the instrument one of the prominent microscopists 

 of the present day says ; " These turn tables are as nice and neat 

 and beautiful as can be imagined." To all of this I agree, but 

 what is of still more importance is the fact they are more con^ 

 venient, useful and necessary, than can be imagined. I do not 

 think that those who mount specimens and finish the slides oflf 

 without the use of the turn table can imagine how useful it is, 

 or each operator would immediately purchase one. I am of the 

 opinion held by the editor of the American Naturalist in 1876 

 when he wrote : " If the real convenience of the turn table were 

 known it would soon become general." 



All the turn tables of the present day consist essentially 

 of a disk supported on a perpendicular axis so that it can be 

 easily and rapidly rotated. A hand rest is attached for the pur- 

 pose of steadying the brushful of cement, while it is applied to 

 the glass slip which can be temporarily fastened to the revolving- 

 disk. The first turn tables, which were made about twenty 

 years ago, had the disk supported on a blunt rod, but as the 

 man of the stone age learned to sharpen his weapon, so the 

 manufacturers have found that the disk will turn more readily if 

 ihe rod is pointed. 



