A Letter from William Molyneux Esq; To One of the Secretarys of the R. S. concerning the Circulation of the Blood as Seen, by the Help of a Microscope, in the Lacerta Aquatica

sible at $A$, and only $A, B, C$ at $E$; or wherein $B, D, E$, may be visible at $A$, and only $C, F, A$, at $E$; or wherein $A$ may be of one side of the quadrilateral, and $E$ on the other; or one of the stations within the quadrilateral, and the other without it: I shall for brevity's sake omit the figures, and diversity of the Signs + and -- in the calculation, and presume that the Surveyor will easily direct himself in those cases, by what has been said. The Solution of this third problem is general, and serves also for both the precedent. For suppose $C, D$ the same point in the last figure, and it gives the solution of the second problem: but if $B, C$, be suppos'd the same points with $D, F$, by proceeding as in the last, you may directly solve the first problem. --- A Letter from William Molyneux Esq.; to one of the Secretarys of the R. S. concerning the Circulation of the blood as seen, by the help of a Microscope, in the Lacerta Aquatica. Dublin Octob. 27. 1685. Sir, OUR Society lately received transcripts of two of Dr Gardens Letters, the first dated form Aberdeen July 17. 1685. to Dr Middleton; the other Sept. 4. 1685. to Dr Plot. To both these Letters I have something to say. In the first he gives an Account of the Visible Circulation of the blood in the Water-Newt or Lacerta Aquatica; truely I am heartily glad, that this Learned and Ingenious Dr has hit upon this Experiment; tis now above two years and an half, since I first Discovered this surprising prising appearance, and wrote a large account thereof May 12. 1683, as also of the whole Anatomy of this Animal, to my Brother, who was then at Leyden. And I have since that shew'd it frequently, both on the outside without Dissection, and in the inward Vessels also, to several Curious Physicians and Philosophers, to their great satisfaction and admiration; particularly I exposed it first to our Society May the 26. 1684, as appears by the following Minute taken from our Registry. May 26. 1684. Mr. Molyneux opened before the Company a Water-Newt, which he takes to be the Salamandra or Lacerta Aquatica, in the body of this Animal there are two long Sacculi Aerei, on which the blood Vessels are curiously Ramifyed, to these blood Vessels applying a Microscope, he shewed the Circulation of the blood ad Oculum, as plainly as water running in a River, and more rapidly than any common Stream. The same experiment I repeated again before them on the 2d of June following, and to those that had good observing Eyes, the Circulation was as visible outwardly on the hands and toes, as in the Vessels within. But Certainly the Appearance in the Vessels on the two forementioned Sacculi, with the beating, emptying & filling of the Heart, is most surprising to the beholder. This Creature seems wonderfully adapted by Nature for this Experiment; for besides the transparency of its Skin and Vessels, I have had them live nine hours after they have been Expanded, and all their Viscera laid open. I fend you herewith the Figures of the Animal. Fig. 7th. Tab. 1. shews the Entire Body of a Male, for the Female is not so strongly spotted. Fig. 8th. Tab. 1. is Rudely drawn, but a a Represent the Sacculi Aerei. To Dr Gardens 2d Letter I have only this, he in-deavours therein to explain and give an Account of the Trade Winds within the Tropicks from the different gravity of the Atmosphere at divers times of the Year. And yet it is asserted numb. 165. pag. 790. of the Philof. Transatlions. Transactions, that the Mercury is not affected with the weather, or very rarely, let it be Cloudy, Rainy, Windy, or Serene in St Helena, or the Barbadoes, and therefore probably not within the Tropicks, unless in a Violent storm or Hurricane. Now if the Mercury move little or nothing in the Baroscope, tis likely there is little or no Change in the Gravity of the Atmosphere within the Tropicks. I am, Your most Humble Servant, WILLIAM MOLYNEUX. Part of a Letter from Dr. Nath. Vincent. F. of the R. S. concerning Dr Papin's way of Raising Water. I have inquired into Dr Papin's Problematic Engine for raising Water, in the Transaction of July 1685, and do conclude it may be solved after this manner. Within his Rock G C (see Phil. Transf. Num. 173, Fig. 18th.) there may be a Vessel placed, which shall be made like the Body of a pair of Bellows, or those Puffs heretofore used by Barbers, which being filled with water, a piece of Clock-work put under it may produce the Jetto's; the water being received into the Shell HH, and running thence into the hollow of the Coral EE; may be thereby conveyed into the follicular cavity, in the same quantity it is ejected from the two Emerging