340 Dr George Wilson on the Earli/ History of the 



a particular end of his own,""* but are, nevertheless, de- 

 scribed, with few exceptions, as if a continuous portion of 

 Boyle's special researches. 



I cannot give the original date of the Latin or English 

 editions of the tract, but the experiments are all dated. The 

 first bears date July 11, 1676, the last February 17, 1679. 

 Papin's air-pump which he brought with him, is therefore, at 

 least, as old as 1676, which maybe considered the date of its 

 introduction into England. Its great peculiarity, as contrast- 

 ed with former air-pumps, was, that it had two barrels. It 

 was, according to Boyle, Papin^s own contrivance. The for- 

 mer, referring to the use he made of the latter's mechanical 

 devices in prosecuting his researches, says, — " Not a few of 

 the mechanical instruments (especially the double pump and 

 wind-gun), which sometimes were of necessary use to us in 

 our work, are to be referred to his invention, who also made 

 some of them, at least in part, with his own hands."t 



Papin''s air-pump was a curious machine. It is represented 

 in fig. 4, taken from the plate in Birch's Boyle, vol. iv. (end 

 of the volume^, which represents only 

 the working parts of the instrument, 

 without the frame supporting them. 

 It had two pumps standing side by 

 side, with the mouths of the barrels 

 A A, turned upwards. Each of the 

 piston rods C C, terminated in, — as 

 it is styled in the original, — a stirrup 

 DD, attached to its upper end, and the 

 stirrups were connected by a rope or 

 cord E, which passed over a vertical 

 grooved wheel or large pulley F. To 

 work the machine, the exerciser of 

 the pump, as he is called in the ori- 

 ginal account, put his feet into the 

 stirrups, and holding on, as it should 

 seem, by his hands, to the upper part 

 of the frame-work of the air-pump, or 



Fig. 4. 



* Birch's Boyle, vol. iv., p. 506. 



t Op. cit., p. 507. 



