ON ARTIFICIAL REFRIGERATION. 945 



course, led me in early days, when seeking practical improvements in 

 ice-machines, to search for a continuous-motion or rotary pump, without 

 clearance, capable of passing gases of great tenuity, at all pressures. 



The obstacles in my way have been well understood by engineers, and 

 I cannot do better than indicate them by a sweeping declaration at page 

 3G7 of Professor Thurston's History of the Growth of the Steam Engine. 

 He says: "The rotary engine is gradually coming into use for various 

 sjiecial purjioses, where small power is called for, and where economy of 

 fuel is not important ; but it has never yet competed, and may perhaps 

 never in the future compete, with the reciprocating-piston engine where 

 large engines are requked, or where even moderate economy of fuel is 

 essential." 



I had grown to believe not a little as Professor Thurston exi^resses 

 himself, when in the summer of 187G I was told by Mr. Siebe, son of 

 the celebrated Daniel Siebe who first built the successful Harrison ether- 

 machine, that what I had so long searched for had at last been invented 

 by a Lancashire engineer. Mr. Siebe had seen an engine and j)ump 

 working, in the compression of air, up to 60 pounds, and drawing a 

 vacuum up to 28 inches ; and this same apparatus I shortly afterwards 

 purchased from Mr. William Eli Sudlow, the inventor and patentee. 



Familiarity in working turbines of various kinds, in connection with 

 cotton and woollen mills in Mexico, led Mr. Sudlow to a close study of 

 the methods whereby steam could be used in a revolving engine. In 

 Central America he failed with his first castings, and, with the genuine 

 enthusiasm of a pioneer, he threw up his lucrative position to return to 

 England and complete his work. He first built a five-cylinder engine, 

 which was exhibited at the Peel Park Manchester Exhibition in 1874. 

 Both "Engineer" and '• Engineering" favorably noticed this effort of 

 striking novelty, but the unwieldy nature of the apparatus led to its being 

 superseded, by a series of progressive improvements. To such perfection 

 had Mr. Sudlow brought his air-pumps and steam-engine in 1877, that I 

 asked him to accompany me to America, with an apparatus which is the 

 most perfect gas-pumping arrangement that I believe has ever been pro- 

 duced. 



It consists of two pumps capable of passing 90 cubic feet of gas per 

 minute at atmospheric pressure, the pumps being driven by an engme 

 which is placed on the same shaft. 



Both engines and pump are of identical construction, except as to the 

 arrangement of valves. They rest in line on a common bed-plate, and 

 the description of one cylinder will serve for all. 



The cylinder is extended upwards by a rectangular block, and is pro- 

 vided at its ends with closely-fitting covers having ample stuffing-boxes, 

 suitably i^acked. 



On removing an end cover an internal piston-cover, circular in form, 



comes into view. This piston-cover fits into a recess where it is packed 



by metallic rings like an ordinary piston. Above this cover is a rectaugu- 

 60 F 



