230 HOW TO SEE WITH THE MICROSCOPE. 



other glazed openings in the room liable to form cross- 

 lights, they should be closed by shutter or curtain. 

 The table selected should be solid and heavy. Any and 

 all of the little light affairs in cherry and mahogany 

 offered at the furniture stores are totally unfit for a mi- 

 croscope table; but the crowning nuisance of the lot is 

 the revolving table, made expressly for the microscopist, 

 and sold at outrageous prices. Castors, also, are to be 

 rejected. In short, anything that detracts from the sol- 

 idity or rigidity of the work-table is to be eschewed. 

 What the observer wants is a firm support for his stand, 

 free from shake or tremble one that he can lean against 

 freely when weary, and one that he may even run against 

 accidentally without inaugurating any serious calamity. 

 A couple of drawers placed in the front are a convenience 

 for storage of accessories, etc., and these, being partly 

 opened, form convenient rest at times for the forearm. 

 The table should be sufficiently large and roomy. Three 

 by four feet is none too large. 



THE SPENCER ONE-INCH OF 50 BROAD-GUAGE OBJECT- 

 IVES, ETC. 



In the spring of 1878 we received from the Messrs. 

 Spencers an inch objective of 50 aperture. This glass 

 was made expressly to our own order. 



Our purpose in ordering the above glass was to deter- 

 mine whether it was possible for the Messrs. Spencers 

 to furnish an inch objective having angle and definition 

 equal to their celebrated two-thirds. 



With the new inch our experience has thus far been 



