Some Reflections on Mr. De Lisle's Comparison of the Magnitude of Paris with London and Several Other Cities, Printed in the Memoirs of the Royal Academy of Sciences at Paris for the Year 1725. Communicated in a Letter to Dr. Rutty, Secretary to the Royal Society, by Peter Davall, of the Middle Temple, Esq.

Pleasure. For Air, the Country hereabouts has always and deservedly, been reckoned the Montpelier of England; for Water, Wood, Heath, and Prospect, it may be thought the Frescati. I am Your most obedient Servant and Brother, William Stukeley. III. Some Reflections on Mr. de Lisle's Comparison of the Magnitude of Paris with London and several other Cities, printed in the Memoirs of the Royal Academy of Sciences at Paris for the Year 1725: Communicated in a Letter to Dr. Rutty, Secretary to the Royal Society, by Peter Davall, of the Middle Temple, Esq. Mr. de Lisle in the Account he gives of his Method of making an exact Plan of Paris, and comparing it with London, and other Cities, first shews, by what Means he proceeded in determining, and laying down the true Situation of the several Places in Paris: After which he explains his Manner of drawing a true Meridian Line through that City; whereby he he was enabled to divide it by Meridians and Parallels, as is practis'd in a general Map: And then he goes on in the following Words; "I traced the Parallels from 15 to 15 Seconds, and the Meridians from 20 to 20. And, as under the Parallel of Paris, 15 Degrees of Latitude are equi- valent to 20 of Longitude, and the like is true of Minutes and Seconds; by allowing 5 Seconds more to the Intervals of the Meridians, than to those of the Parallels, I form'd perfect Squares." He says, the chief Use he intended to make of these Squares, was to compare the Magnitude of Paris with that of London, and gives an Account of what Method he took to procure a just Plan of this City, which he reduced to the same Scale as that of Paris, and proceeds thus: "I traced upon it in like Manner, Squares from 15 to 15 Seconds of a great Circle, and then I was prepared to compare the Greatness of the two Cities." "The Result of this Comparison is, that Paris con- tains 63 of these Squares, which makes for its Su- perficies 3538647 square Toises: And that Lon- don contains only 60 of those Squares, or 3370140 square Toises." And from hence he concludes, that Paris is one twentieth Part greater than London, tho' he says he has excluded several Gardens, contained within Paris, out of this Mensuration, which would have made it bear still a greater Proportion to London. Upon reading this Account of Mr. de Lisle's, it immediately occurred to me, that the Method which he has here taken of comparing the Magnitudes of Paris and London, from whence he infers that the first of these Cities is one twentieth greater than the latter, is founded on a false Supposition, viz. That under the Parallel of Paris 20 Degrees of Longitude are equal to 15 of Latitude, and consequently that by drawing Meridians from 20 to 20 Seconds, and Parallels from 15 to 15, the Figures formed by their Intersection will be perfect Squares: For the Equator and its Parallels are to each other as the Sines of their respective Distances from the Pole. Whence, as the Radius, or Sine of 90 Degrees, is to the Sine of the Distance of any Parallel from the Pole, or Cosine of its Latitude :: so is a Degree or any other Part of the Equator, or of any great Circle, to the like Part of the given Parallel. Therefore taking the mean Latitude of Paris at 48°. 51', the Proportion of the Degrees of a great Circle to those of the Parallel of Paris will by a Table of Sines be found to be as 1 to .6580326. Whereas according to Mr. de Lisle, that Proportion is only as 20 to 15, or as 1 to .75. The Figures therefore which Mr. de Lisle calls Squares, are not such, but Rectangles, whose longest Side containing 15 Seconds of a great Circle, bears the same Proportion to the shortest, containing 20 Seconds of the Parallel of Paris, as .75 does to .658, &c. or nearly as 8 to 7. And the Intervals, which he ought to have allowed to the Meridians, to make perfect Squares of these Figures, ought to have been 22' 4" or 22' 48" of the Parallel of Paris. Now Mr. de Lisle says, these Figures are perfect Squares, and has computed them as Squares, whose Side was 15" of a great Circle; for he says Paris contains 63 of these Squares, which makes 3538647 square Toises, Toises, which last Number being divided by 63, the Quote 56169 will be the Number of square Toises contained in each Square, whose square Root gives 237 Toises for the Side of each Square, which is just 15" or \( \frac{1}{4} \) of a Degree of a great Circle. Mr. de Lisle hath therefore by this Account made the superficial Content of each Rectangle, and consequently of the whole City of Paris too great by near one seventh. To confirm which beyond Contradiction we have Mr. de Lisle's own Testimony, who in the Plan he himself has drawn and published of Paris, and which he refers to in this very Account, has not made Squares of the above-mentioned Figures, but has given to their respective Sides the Proportion of 8 to 7, which is as near the true one as can well be express'd by Lines, in a Plan of no larger a Scale than this. Now in the Account we have been considering, Mr. de Lisle says himself, that in his measuring of London he drew Squares, whose Sides contained 15 Seconds of a great Circle, and of these he says, London contains sixty. Therefore to compare Paris with London, we ought for the foregoing Reasons to make an Abatement out of the 63 Rectangles which Paris contains, nearly in the Proportion of 8 to 7; but because that is a little greater than the true one, let us make such Abatement only in the Proportion of 9 to 8, which is pretty considerably less than the just one. By which Abatement the Number of Squares, whose Side is 15 Seconds of a great Circle contained in Paris, will be reduced from 63 to 56. And consequently, according to Mr. de Lisle's own Way of measuring, the Magnitude of London will be to that of Paris as 60 to 56, or as 15 to 14; or London will be one fourteenth greater than Paris. But to determine what Proportion these two Cities really bear to each other, requires a more exact Mensuration of London than any we yet have, which whoever would undertake, I think he cannot follow a better Method than that Mr. de Lisle has taken, and would advise him to consult the Account upon which the foregoing Reflections are made, which he may find in the Memoires of the Royal Academy of Sciences, for the Year 1725. Pag. 48. IV. An Account of an Aneurysm of the Aorta, (dissected in St. Bartholomew's Hospital) by Pierce Dod, M.D. Fellow of the College of Physicians, and Physician to that Hospital. An Aneurysm, without Doubt, is a Tumour arising from some Disorder in an Artery; but what that Disorder is, or whence it arises, is not so well agreed, the Accounts which are given of it, being widely different and uncertain. The Name seems to imply, that it is a Dilatation of the Vessel; but Galen describes it to be a Tumour, which arises not from any Dilatation or Relaxation of an arterial Vessel, and the Blood therein contain'd; but from an Extravasation of the Blood from some Rupture of the Artery. Agree-