VOL. XIV.] PHILOSOPHICAL TBANSACTIONS. 23 



The Explanation of the Figure of the Polypus, as it appeared when fresh ex- 

 panded on a Board. Fig. A, pi. 1 . — A that part of the polypus which was firmly 

 rooted in the right ventricle of the heart. B the branch terminated in the 

 right auricle. CDDD the part tending toward the lungs. EE the branch 

 running out of the ventricle into the pulmonary artery, eeeee, &c. The several 

 lesser ramifications, distributed according to the several divisions of the pulmonary 

 artery. FFF the branch belonging to the descending vena cava. GG the 

 branches begun in the axillary veins. HHHHH, &c. the two branches that 

 ran up the internal jugulars, even to their entrance into the skull. hhTwo 

 little black specks of concreted blood, contained within the coat of the 

 polypus. 



An Account of a Booh, viz. The Geometrical Key, or Construction of all Equa- 

 tions, Linear, Quadratic, Cubic and Biquadratic, by a Circle and one only 

 Parabola. By Mr. Thomas Baker, Rector of Bishop Nympton, in Devonshire. 

 N° 157, p. 549. 



The analysis which the ancients used for constructing problems geometrically, 

 or by lines, has been highly advanced by Descartes's method; that part of this 

 method which concerns local problems has been well explained by De Wit, but 

 the other and more principal part of constructing equations has been lately 

 cleared by De la Hire. Yet neither Descartes nor De la Hire do it without the 

 trouble of preparing the equation by taking away the second term. To avoid 

 this trouble our author here shows how to construct all afl^ected equations, not 

 exceeding the 4th power, by the intersection of a circle and parabola, without 

 omitting or changing any of the terms. And although by the method of 

 Descartes we may find not only any parabola, but also ellipses and hyperbolas, 

 to construct these equations, yet of all lines of the first kind, a circle and para- 

 bola being the most simple, it follows that the way which our author has chosen 

 is the best. 



A Letter from Mr. Wm. Molyneux, Secretary to the Society of Dublin, to iVm. 

 Mmgrave, L. L. B. Fellow of Neiv College, and Secretary to the Philosophical 

 Society of Oxford, for the Advancement of natural Knowledge ; concerning 

 Lough Neagh in Ireland, and its petrifying Qualities.* N° 138, p. 552. 



It is generally agreed by all the inhabitants thereabouts, that Lough Neagh 

 has a petrifying quality ; yet I have a letter by me from a gentleman (unknown 



* On the petrifying quality of this lake, further observations occur in some of the subsequent 

 volumes of the Transactions ; among which, those by Mr. Simon in the 44th volume deserve 

 particular notice. 



