336 PHILOSOPHICAL TRANSACTIONS. [aNNO l66g, 



on comparing their several sentiments on this subject, that theory might be 

 adopted which should be found to agree best with observation and experiment, 

 carefully made and often repeated. 



Upon this M. Huygens, Dr. Wallis, and Dr. Christopher Wren, members 

 of the Society, were induced to finish and complete their several hypotheses and 

 laws of motion, in forming of which, they had spent some time : And in a few 

 weeks after these excellent persons transmitted to the Royal Society elegant ab- 

 stracts of their theories, desiring the sentiments of that illustrious body upon 

 them. Dr. Wallis was the first, who in a letter dated Nov. 15, and read be- 

 fore the Society the 29th, 1668, had communicated his principles of estimating 

 the motion of bodies. Dr. Wren in a little time after, viz. 17th of Dec. of the 

 same year, imparted to the Society, his law of nature on the collision of bodies ; 

 and the Society ordered, after first obtaining the permission of the authors to 

 publish these discoveries, that they might be more conveniently communicated 

 and more fully discussed. In the mean time, viz. on the 4th of the ensuing 

 January, Mr. Oldenburg had a letter from M. Huygens dated Jan. 5. N. S. 

 containing the first four rules concerning the motion of bodies after mutual im- 

 pulse, together with their demonstration. And that very day on which Mr. 

 Oldenburg received M. Huygens' letter, he sent in return a copy of Dr. Wren's 

 theory without opening M. Huygens', which, on account of its bulk, and that 

 gentleman's former promises, he suspected to contain something on the same 

 matter, till he should have an opportunity of seeing the Honourable Lord 

 Viscount Brounker, president of the Society. After which, and on comparing 

 the rules of both, the Society found *a surprising coincidence, which made them 

 more inclinable to a publication of them ; and nothing more seemed to be want- 

 ing but M. Huygens' consent, without which it was not thought proper to 

 publish his discoveries, especially as they were not then entire. In the mean 

 time it was ordered that they should be laid up in the public archives of the 

 Royal Society, and at the same time that thanks be returned to the author for 

 bis frankness in communicating them ; and on the 4th of February following 

 he was earnestly intreated to publish his theory, either at Paris in the Journal 

 des Scavans, or at London in the Philosophical Transactions ; and in a little time 

 after, Mr. Oldenburg had a second letter from M. Huygens, approving Dr. 

 Wren's theory, without making any mention of the publication of his own, 

 either at Paris or London. Hence it appears that M. Huygens was wanting to 

 himself in delaying that publication, thus giving occasion to Dr. Wren, who 

 by the sagacity of his own genius had made the very same discoveries, to claim 

 a just title to some share of the glory of the discovery ; since it is plain, that 

 neither of them had known any thing of each other's theory, before they were 



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