and Laboratory Methods. 



2563 



The times of taking the temperature were separated by an hour's interval ; the 

 first two tables were observed on two similar desk cases, respectively near and 

 removed from a radiator, and the last table observed on a wall case. Mr. 

 Hindshaw's contention receives confirmation. 



The groove and tongue device is very thorough, but rubber for the latter is 

 not permanently serviceable. It dries and loses coherence and after a time fails 

 to fit the srroove. 



Fig. 



A thorough and comprehensive protection against dust is the introduction in 

 the museum structure of the systems of ventilation involving filtered air. This 

 of course means a greater initial expense, and it means, as a consequence, 

 increased running cost. Such systems, rather sparingly introduced into build- 

 ings at first, are now more gratefully recognized as agreeable features. The air 

 is propelled by fans, and comes in contact with wet surfaces of cloth or cotton 

 batting, and is thus freed measurably of its dust burden. The ideal application 

 of this system implies its use in summer as well as winter, which might seem to 

 some an almost insuperable objection to its adoption. 



Group cases are those cases especially adapted for individual exhibits, usually 



