FRUIT STORAGE 1 33 



the case of the cellar built by Professor Alwood, the 

 excavation is only lo feet deep at the deepest point, 

 but he now feels satisfied that a greater depth would 

 give better results. The principle of a subterranean 

 air flue is the unique feature of this cellar. Its use 

 is intended to secure a dry, even temperature in the 

 cellar by admitting air as desired through this flue. It 

 should be at least 6 inches in diameter, and should be 

 laid at a depth of 8 or 9 feet for a distance of about 

 500 feet. 



It is not necessary that this flue should lie in a 

 straight line, but any departure from a straight line 

 should be a gradual curve, so as to permit an unob- 

 structed flow of air into the cellar. Situated at this 

 depth and having .a length approximately as stated 

 above, the air flowing into the cellar through this flue 

 will be in summer reduced, and in winter raised, to the 

 temperature of the soil at the depth stated, which will 

 approximate somewhere between 50° and 55" Fahren- 

 heit during the entire year. The above statement is 

 based on the observed temperature of perennial springs 

 in the vicinity of Blacksburg, Va. 



From the foregoing it follows that if the air in the 

 cellar becomes warmer than the air in the underground 

 flue, it will rise through the ventilating flues, and the 

 colder air will flow in from the supply flue as desired. 

 The temperature of the cellar room can thus be approxi- 

 mately controlled down to at least the neighborhood 

 of 55° to 60° Fahrenheit. 



The construction of the cellar is shown somewhat 

 in detail in the drawings. These figures serve to 

 bring out the essential ideas and plan of the structure 



