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finger. The ice is broken up in the ice room and hoisted to 

 the attic in a large bucket holding some 400 or 500 pounds. 

 This bucket, filled with ice, is then run along on a track 

 (which extends the whole length of the penthouse) until it 

 stands directly over the bunker to be filled, when it is tipped 

 and the ice dumped into the bunker. Salt is then thrown in 

 on top of this ice, another bucket of ice is put in, followed by 

 more salt, and so on till the bunker is full. The amount of 

 salt used varies with the temperature desired and with the 

 outside temperature. It will ordinarily run about 5 to 8 

 quarts to each bucket of 400 pounds of ice. If at one icing 

 6 quarts of salt have been used and the temperature has not 

 run quite low enough, more salt is used at the next icing. 

 The temperature is also regulated by the valves located in 

 the storage rooms which control the flow. If more " cold " 

 is desired these valves are opened; if less, they are closed. 

 With a little experience the system can be run very easily 

 and very accurately. In our college plant the work is prac- 

 tically all done by the ordinary day laborer of the depart- 

 ment. The foreman merely keeps track of the temperature 

 from day to day, and gives directions as to the quantity of 

 salt. 



As to the working of the system, it is exactly the reverse 

 of the ordinary hot-water heating system used in dwelling 

 houses. In the latter the furnace is located in the cellar 

 and heats the water, thereby rendering it lighter. This light- 

 weight hot water then flows out through certain pipes and is 

 replaced by the heavier cold water which comes down through 

 other pipes from the rooms above, where it has been cooled 

 off, or, in other words, where it has heated the air of the 

 rooms. IJ^ow in this gravity-brine system the brine is cooled 

 by the ice and salt in the bunkers and is thereby rendered 

 heavier. It therefore flows down, and by its greater weight 

 forces out the warmer brine in the secondary coils of the 

 storage room, and is itself warmed up by absorbing the heat 

 of the room and its contents. The frequency with which 

 icing is required depends on the outside temperature, on the 

 temperature desired in the rooms, and also on the frequency 



