and Laboratory Methods. 



2609 



cession made to variety and contrast. The installation of gems, indeed, is an 

 artistic question, and with very handsome collections, may be advanced to a 

 higher note of beauty and elegance. 



It will be found attractive in gem rooms to provide small square or oblong 

 table cases, rather deep (8 to 12 inches), and arrange a different gem stone in 

 each, cut material being placed in front, or to one side, and the uncut at the 

 back, or opposite side. Uncut material may also be placed in upright cases 

 above the flat case containing the cut stones. The finished and carved vessels 

 of quartz, jade, fluorite, rhodonite, jasper, heliotrope, etc., etc., should be grouped 

 in special cases with glass superimposed shelves, so that all sides can be in- 

 spected. If cut objects of this sort are exhibited in wall cases, the backs of the 

 cases should be mirrors. 



Fig. Ho. — Transparencies in window, A. M. N. H. 



Gem rooms should have electric alarms, and be protected by strong iron 

 gates, with the provision of a constant watchman. 



The use of transparencies in windows illustrating geology, mineralogy, eth- 

 nology, etc., is most admirable if not pushed so far as to be an obstruction to 

 the illumination. They may be put into wooden frames, and if of the same height 

 held in place by cross bars of wood attached to the sash mouldings. They may 

 also be held in place by elbow irons screwed to the sash of the window and 

 screwed to the frame of the transparency (Fig. 93). 



In cases where very small objects, as little shells, minute crystals, intricate 

 orfeverie, illuminated missals, or sometimes photographs, etchings, etc., are 

 exhibited, some adjustment should be adopted for bringing the specimens nearer 

 the glass of the sash. The most simple device, and one entirely adequate, is to 

 put in a flat case compartment a false bottom of the exact size of the compart- 

 ment. Again, some of the small objects amongst the larger ones can be raised 

 upon pedestals. A very excellent and helpful feature, and one which is hardly 



