126 



THE AMEKICAN MONTHLY 



[July, 



A New Illuniinator. 



Some time ago the Bausch & Lomb 

 Optical Company introduced a new 

 form of illuminator for the sub-stage, 

 which is illustrated in fig. 21. We 

 have reserved particular reference to 



necessary in explanation of the cut. 

 We would judge from the appearance 

 of the instrument that it would be 

 efficient, and at the same time inex- 

 pensive to purchase. 



For ourselves, we like a turn-table 

 that will run for a considerable time 



^f^^"^^ 



Fig, 



this accessory for some time, hoping 

 to be able to prepare an article on the 

 subject of illumination, but as oppor- 

 tunity has not yet offered for writing 

 such an article we figure the instru- 

 ment in this place, and will take oc- 

 casion to refer to it again in future. 



It will be seen that the condenser 

 is intended for universal use ; dia- 

 phragms of various forms can be 

 placed in the carrier to give dark- 

 field effects, or oblique light from 

 different azimuths, and in addition 

 there is another diaphragm for ob- 

 lique light, shown in the left-hand 

 figure. 



Mr. Orifflth's Turn-table. 



The illustration of the turn-table 

 recently introduced by Mr. E. H. 

 Griffith was inadvertently left out of 

 last month's issue. It is now shown 

 in fig. 22, and no description seems 



without constant urging. For 

 this reason a heavy face-plate 

 is necessary, and Mr. Griffith 

 seems to have carried out the 

 idea by the heavy balls sup- 

 ported from the periphery of 

 the plate. The advantage of 

 good momentum is found prin- 

 cipally when it becomes necessary to' 

 turn oft' a ring of hard cement with 

 the point of a knife. A light wheel 

 would not do for such work, which 

 is easily done on some turn-tables. 

 o 



A New Design for a Microscope 

 Cabinet. 



BY C. E. BEECHER. 



A good cabinet bears nearly the 

 same relation to the slides that the 

 cover of a book bears to the contents. 

 A valuable book is worthy of a fine 

 binding. Literary trash merits the 

 yellow cover it usually receives. A 

 fine collection of mounted objects 

 should have a becoming receptacle 

 for its pi'esei-vation. 



Two large cabinets, made after the 

 following design, have been in con- 

 stant use for three years, and have 

 given such satisfaction that I consider 

 it of sufficient importance to make 

 known their construction. At pres- 

 ent there is a great demand for 

 cheap cabinets, but none of them, 

 so far as I know, are very satis- 

 factory for working collections. 

 They are serviceable more for the 

 reception of duplicates or other 

 objects which are not often re- 

 ferred to. 



The accompanying figures (Fig. 

 23) show the principal details of 

 construction, and require little 

 explanation. The double-point- 

 ed tacks can be made of brass 



