ON ARTIFICIAL REFRIGERATION. 941 



of physical state from tlie liquid to tbe gaseous. Joule originally de- 

 clared tliat no cliamje of temperature occurs ichen air is allowed to expand 

 in such a manner as not to develop mechanical poiver. Later experiment:^ 

 by Joule and Sir William Thomson indicate, nevertheless, a slight cool- 

 ing efl'ect. 



Some remarkable natural phenomena are attributable, however, to 

 conditions under which air may be compressed and forced through ob- 

 structions, so that its heat may be transformed into mechanical energy, 

 and thus it cools wells or actually freezes water in subterranean caverns. 

 The frozen well at Brandon, Vt.,* has been examined by Prof. JohnM. Ord- 

 way, and is an interesting example of this description. Cold air is con- 

 stantly llowiug upward in it. At the opening of the well the thermom- 

 eter indicated 43^.5 Fahr., the temperature of the external air being 

 78° at the time of the examination. Five feet below the mouth, the 

 thermometer stood at 43*^, and 12 feet down, at 40°. Water drawn out 

 from the bottom without stoi^ping to cool the bucket was at 34^, and at 

 other times it contained lumi)s of ice detached from the ice-coating lin- 

 ing the well for some 5 feet above the surface of the water. Professor 

 Ordway says : " We had hardly begun to make close observations before 

 it occurred to us that we were dealing with a case of compressed aii", 

 which might be accumulated by some natural subterranean tromp 

 (Wassertrommel) or "Catalan blower," and which passing through the 

 gravel effects the gradual refrigeration and actual freezing of a consid- 

 erable quantity of wet gravel." 



To Dr. John Gorrie (American Journal of Science and Art, vol. x, 

 page 39) we owe the earliest determinations of the quantity of heat 

 evolved from atmospheric air by mechanical compression with a \'iew to 

 the production of ice by machinery. He directed attention to the dis- 

 crepant statements of CoUadon, Gay-Lussac, Dalton, and others, and 

 having secured the cooperation of capitalists for the erection of air- 

 compressing appliances in New Orleans, he chanced to adopt the only 

 method by which any success, by this method, in artificial refrigeration 

 was possible. The compressed air Avas allowed to discharge into an 

 engine w^hich worked expansively through a valve so constructed as to 

 permit of cutting off the communication with the reservoir at any portion 

 of the stroke. The air, in this way, independently of the safety-valve, 

 was prevented from attaining more than a certain degree of pressure. 

 Dr. Gorrie anticipated later patents in which the injection of water to 

 cool the air in the comi)ressing-pumj) has been practised. Indeed, he 

 studied the subject with skill and in^ true philosophic spirit, complain- 

 ing that "owing to defects of mechanical contrivance and unskilful 

 workmanship, incidental, perhaps, to every new device and a novitiate 

 intercourse with practical mechanics, the machine was not capable of 

 performing all its duties with the accuracy the natiu^al laws involved 

 called for." 



* Ann. Sci. Discoveries, 1856, p. 190; 1860, p. 316. 



