346 Dr George Wilson on the Early History of the 



double air-pump in his possession till 1676, when he made 

 use of Papin's. Mr Weld's date of 1662 can only apply to 

 Boyle's pneumatical engine, completed in 1659. We have 

 direct evidence, however, of the most weighty kind, to shew 

 what the instrument really was which Boyle presented to the 

 Royal Society. In his " Continuation of new experiments 

 Physico-Mechanical, touching the Spring and Weight of the 

 Air ; Oxford 1669,'' already referred to, as containing the 

 description of his second pneumatical engine, the following 

 passage occurs : — " Being obliged to make some journeys and 

 removes, which allowed me no opportunity to prosecute the 

 experiments, I had made no very great progress in my de- 

 sign before the convening of an illustrious assembly of vir- 

 tuosi, which has since made itself sufficiently known under 

 the title of the Royal Society. And having then thought fit 

 to make a present, to persons so like to employ it well, of 

 the great engine I had till then made use of in the physico- 

 mechanical experiments about the air,"* &c. This decides 

 both what the instrument was, and within certain limits the 

 date of its being given to the Society. t It was the first or 

 great pneumatical engine of 1659, and was presented to the 

 virtuosi before their incorporation as the Royal Society, 

 which took place on the 15th of July 1662. J 



Further evidence is not required ; but it seems well to 

 notice, since a claim is set up for Hooke, as having made a 

 double-barrelled pump in 1660, or before 1662, that we have 

 what amounts to a disclaimer of this from him. Waller, in 

 his life of Hooke (p. iv.), after quoting a statement of the lat- 



* Preface, i., ii. 



t According to the statement of Dr Birch, already given {History of Royal 

 Society, vol. i., p. 23), the pneumatical engine was presented to the Royal Society 

 more than a year before its incorporation, viz., in May 1661. Weld, in the 

 note already quoted, refers to the gift as having been made in 1662. I know 

 not how to reconcile these conflicting statements of the Secretaries, who both 

 speak with authority, and in reliance on the same official documents. The dis- 

 crepance, however, is immaterial to my present purpose, as all parties agree in 

 making 1662 the^latest possible date of the presentation of the first air-pump 

 to the Royal Society. 



I Weld, vol. i., p. 121. 



