342 Dr George "Wilson on the Ear It/ His ton/ of the 



loading, ramming, priming, and firing the two barrels, which 

 are independent in action though lying side by side. In the 

 air-pump, on the other hand, the working of the one piston 

 renders more easy the working of the other, and diminishes 

 the time requisite for the working of both. It is the connec- 

 tion of the pistons, not the association of the barrels, that 

 effects tliis result. It might have been well, therefore, if the 

 instrument had been called, not the double-barrelled, but the 

 twin-piston air-pump. 



It is not a little singular that Papin's machine should have 

 been overlooked by most later writers. I have not found it 

 referred to in any recent English work of authority, although 

 its curious stirrup arrangement, which has been employed in 

 no English air-pump, might have been expected to direct at- 

 tention towards it. Papin is mentioned incidentally by 

 Nairne. as an improver of the air-pump.* Dr Hutton in his 

 Mathematical Dictionary! mentions Papin's two barrels and 

 twin pistons, but not the stirrup arrangement. 



In Shaw's abridged Boyle, the whole machine is described 

 and figured ; but Papin's name is not once mentioned, an 

 omission which, at the present day, would be considered in- 

 excusable in an editor or abridger. The double pump must 

 pass with Shaw's readers for an invention of Boyle's, yet even 

 the latter's great name has not kept the instrument in remem- 

 brance, a significant proof how little Boyle's works, even when 

 abridged, are read by the very historians of his labours. 



Kecent writers on Pneumatics having overlooked Papin's 

 machine, whilst they universally acknowledge the importance 

 of two barrels, with the pistons counterbalancing each other, 

 have attributed this great improvement to Boyle, to Hooke, 

 or to Hauksbee, an admirable observer, and very inge- 

 nious mechanician, who flourished in the first decade of the 

 eighteenth century. 



Professor Baden Powell, in his interesting History of Na- 

 tural Philosophy, p. 235, says : — " Boyle made the first im- 

 provement, and reduced the air-pump to nearly its present 



* Phil. Trans., 1777, vol. i., p. 636. t 1796, vol. i., p. 55. 



