VOL. LXXXVII.] PHILOSOPHICAL. TRANSACTIONS. I37 



Of the figures marked 9th day, one shows the foetus, now, for the first time, of itself visible to the 

 naked eye, adhering near the tail to the placenta in the closest manner ; the navel string as yet too short 

 to be visible, as contrary to De Graaf as possible. The 2d shows the same foetus magnified. 



The figure N° 10 shows a fallopian tube, on one side of the uterus of the rabbit, with its fimbriated 

 orifice opening into the abdomen : and its uterine orifice opening into the uterus 3 also the ovarium, and 

 corpus luteum in it, projecting above the surface. 



X. Letter from Sir Benjamin Thompson, Knt. Count of Rumford, F. R. S., to the 

 Right Hon. Sir Joseph Banks, Bart., K. B., P. R. S., announcing a Donation 

 to the Royal Society, for the Purpose of instituting a Prize Medal, p. 215. 



" Sir, — Desirous of contributing efficaciously to the advancement of a branch of 

 science which has long employed my attention, and which appears to me to be of 

 the highest importance to mankind, and wishing at the same time to leave a lasting 

 testimony of my respect for the r. s. of London, I take the liberty to request that 

 fhe r. s. would do me the honour to accept of j^IOOO stock, in the 3 per cent, 

 consolidated public funds of this country; which stock I have actually purchased, 

 and which I beg leave to transfer to the President, Council, and Fellows of the 

 Royal Society ; to the end that the interest of the same may be by them, and by their 

 successors, received from time to time for ever, and the amount of the same applied 

 and given, once every 2d year, as a premium to the author of the most important 

 discovery, or useful improvement, which shall be made and published by printing, 

 or in any way made known to the public, in any part of Europe, during the pre- 

 ceding 2 years, on heat, or on light; the preference always being given to such 

 discoveries as shall, in the opinion of the President and Council of the Royal So 

 ciety, tend most to promote the good of mankind. 



" With regard to the formalities to be observed by the President and Council of 

 the Royal Society, in their decisions on the comparative merits of those discoveries, 

 which in the opinion of the President and Council may entitle their authors to be 

 considered as competitors for this biennial premium, the President and Council of 

 the Royal Society will be pleased to adopt such regulations as they in their wisdom 

 may judge to be proper and necessary. But in regard to the form in which this 

 premium is conferred, I take the liberty to request, that it may always be given in 

 2 medals, struck in the same die, the one of gold, and the other of silver; and of 

 such dimensions, that both of them together may be just equal in intrinsic value to 

 the amount of the interest of the aforesaid ^1000 stock during 2 years ; that is 

 to say, that they may together be of the value of *£6o sterling. 



" The President and Council of the Royal Society will be pleased to order such 

 device or inscription to be engraved on the die they shall cause to be prepared for 

 striking these medals, as they may judge proper. If, during any term of years, 

 reckoning from the last adjudication, or from the last period for the adjudication of 

 this premium, by the President and Council of the Royal Society, no new discovery 

 or improvement should be made in any part of Europe, relative to either of the 



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