TUB AIR OF THE LURAY CAVERNS. 



563 



beneficial to the caverns' air. It would be trite to dwell on the advan- 

 tages of lime as a purifier and disinfectant. 



Again, we find no organic matter in the caverns undergoing de- 

 composition, and have on every hand the beautiful, clean, limestone 

 walls and draperies being corroded and reformed by the constant action 

 of myriads of water courses (see Fig. 5). Can we arrive at any other 

 conclusion than that here we have the purest and cleanest atmosphere 

 that can anywhere be found? 



Mr. Northcott 's control of the temperature and humidity conditions 

 is a feature over which the thoughtful visitor must grow enthusiastic. 

 The temperature of the caverns registers from 54° to 56° F. through- 

 out the year, and the relative humidity varies but a fraction of a per 

 cent, from 87. In the hottest summer weather the sanitarium tem- 



FiG. 5. Side View of Ball Room. 



perature ranges from 70° to 7-i° F., and the relative humidity is 

 reduced to 70 per cent, or less, merely by the expansion in volume inci- 

 dent to an increase in temperature from 56° to 70°. In the winter 

 the air is easily raised in temperature from 54° to 70°, and the problem 

 of humidity, while somewhat more complicated than in the summer, 

 is perfectly controlled. As seen in Fig. 1, the air is sent through a 

 boiler-like box of sheet iron (B) and comes in contact with a wide 

 surface of iron tubing, the opposite surface of which is exposed to the 

 cold air outside. This one box failing to reduce the humidity suffi- 

 ciently, there was built a long sheet-iron passageway (D) over the 

 summer air corridor, and by placing a closed door (R) the air is forced 

 through this accessory condenser to be still further robbed of its 

 moisture. 



