208

Gosset and Deuille’s Pump.

[Book II.

No. 83. Gosset and Deuille’s Pump.

A neat and perhaps the best modification of these machines was de-vised about the year 1732, in Paris , by Messrs. Gosset and Deuille. It wasdescribed by Belidor in 1739, and by Desaguliers in 1744, as “a pistonwithout friction.” It consists of a circular piece of leather pressed into

the form of a deep dish, or of a lowcrowned hat with a wide rim. Thisrim is secured by bolts and screwsbetween two flanches of a pump cy-linder, forming an air tight joint—thepart corresponding to the body of thehat fits loosely into the cylinder; andthe crown is strengthed by a circularplate of metal of the same size andriveted to it. In the centre of thisplate an opening is made and alsothrough the leather für the passageof the water, and covered by a valveopening upwards like the ordinarysucker of a pump. The forked endof the pump-rod is secured to thisplate. (See figure.) When the rod israised, the bottom of the dish or hatis above the flanch, and when downit is pushed inside out as shown inthe cut. Thus, by alternately ele-vating and depressing it, the water is raised as in the common pump.This piston is described in Yol. VI, of Machines approved by the FrenchAcademy for 1732, p. 85, as the invention of M. Boulogne. ,

The great advantage of this pump is in the sucker or piston not rub-bing against or even touching the sides of the cylinder, henee there is nofriction to overcome from that source, and the leather is consequentlymore durable ; but the length of stroke is much less than in commonpumps, it seldom exceeding six or eight inches, lest the leather should heoverstrained in pressing it deeper. Large pumps of this description wereworked in the mines of Brittany incessantly during three or four nionthswithout requiring any repair. India-rubber, and canvas saturated orcoated with it, have been successfully used in place of leather. Somemodifications of the sucker have also been infroduced.

This pump was re-invented in England some years ago, and made con-siderable noise under a new name. See London Mechan. Magazine, andRegister of Arts, 1826-29 ; also the Journal of the Franklin Institute for1831, vol. vii, 193. In 1766, Mr. Benjamin Martin, the well known au-thor of ‘ Philosophia Britannica’ and other scientific works, proposed a gooddouble pump of this kind for the British navy—a figure and descriptionof it may be seen in Vol. XX. of Tilloch ’s Philosophical Magazine.

Dr. Robison, in the second volume of his Mechanical Philosophy, pro-posed what has been named an improvement on the last pump. His de-vice is however little eise than the old bellows pump. A figure of it andhis description are annexed.

A, B, (No. 84) represents a woode'n trunk or cylinder of metal, having aa spout at the upper part, and the lower end closed by a plate, the openingin which is covered by a clack valve E, as in No. 83. To this plate is se-cured the open bottom of a long cylindrical bag, the upper end being fixedto the round board F. “ This bag may be made of leather or of double can-vas, a fold of thin leather or of sheepskin being placed between the two