66 ANNUAL OF SCIENTIFIC DISCOVERY. 



ing power of the machine will be increased. We have thus got an 

 elementary cooling machine, and as before, power is spent in working 

 it. To render this a practicable machine, the first thing necessary is 

 to perform the compressing or heating operation, and the expansion or 

 cooling operation in separate compartments ; the one surrounded by 

 water to abstract the heat generated, and the other surrounded by the 

 substance to be cooled, or from which heat is to be taken. The one 

 compartment being thus very cold and the other comparatively warm, 

 the next thing is to provide means by which the air can be continually 

 transferred from one to the other, without carrying heat from the hot 

 CMiniiartment to the cold. Thus, if the temperature of the hot com- 

 partment be 70 and that of the cold zero, the air must enter the cold 

 compartment preparatory to expansion at a temperature as nearly zero 

 as possible, and in returning to the hot compartment must enter it 

 preparatory to compression, at a temperature as nearly 70 as possible. 

 That beautiful invention of Stirling, the regenerator, or respirator, 

 as it is sometimes called, composed ordinarily of a large quantity of 

 wire gauze, through which the air passes, enables us to accomplish this 

 very perfectly. When the machine is fairly agoing, the layers of gauze 

 next the cool compartment become as cold as the compartment itself, 

 and those next the hot compartment as hot, while the layers between 

 those shade off through the intermediate grades of temperature. Thus 

 the air in passing from the hot to the cold compartment, warms the 

 gauze and is itself cooled, and the cold air in returning is gradually 

 warmed, cooling the gauze in its course ; and although the air is con- 

 tinually being passed backwards and forwards from the hot compart- 

 ment to the cold, and vice versa, no heat is conveyed by it from the 

 hot end to warm the cold and interfere with the cooling power of the 

 air during expansion. By the help of the diagrams, Mr. Kirk then 

 explained the arrangements by which this was carried out. He con- 

 cluded by saying that the advantages attending the use of this machine 

 were, that no expensive or dangerous fluid was employed, involving 

 risk of fire or suffocation to the attendants ; that the cooling power 

 might by reduced to any extent when required, the consumption of 

 motive power being similarly reduced ; and that cupped leather pack- 

 ings might be employed, which gave so little trouble that in the first 

 machine one worked for four months without being touched. He 

 further stated that the cost of the machine, without boilers, was 700. 

 Mr. Young said he was able to say that the machine was all that 

 was ever expected. Former machines they had used always kept 

 tlu'm in a state of bodily terror, and once they had a slight fire; but 

 by using this new machine fnere was no longer any cause for fear. 

 The machine was an extraordinary success. It went on day and 

 liight, without intermission and without trouble. With one tun of 

 coal, costing 4s., they could produce one tun of ice. He was glad to 

 1,-e. able to give his testimony to the perfect working of the machine. 

 (Applause.) All manufacturers must hail such a chemical invention. 



HOW TO SETTLE SHIFTING SANDS. 



The Landes in the Gulf of Gascony are composed of loose drifting 

 P:\IM!, v.'huh in 17oi) covered o!X) square miles. M. Bremonticr, of 

 then Administration of Forests in France, set himself to fix this 



