The femoral artery, on its inferior part, just above its division into _tibialis antica_ and _postica_, was diseased; which disease extended four inches upwards. The coats of the artery were considerably thickened, and lacerated longitudinally. The smallest diameter of the diseased part of the artery was two inches and one quarter: the largest diameter of the diseased part of the artery was two inches and one half. Hatton-Garden, Nov. 17. 1757. XLV. _Farther Experiments for increasing the Quantity of Steam in a Fire-Engine. By_ Keane Fitz-Gerald, _Esq; F.R.S._ [Read Nov. 24, 1757.] I Gave a former account to the Royal Society of some experiments made for increasing the quantity of steam in a fire-engine, by blowing air thro’ boiling water[199]. The effects then evidently produced left me, and I believe many others, who came to view the experiments, no room to doubt the seeming cause. In which error I should probably have still remained, had not farther experiments demonstrated the mistake. Whatever apology I ought to make this learned Society, for having given in that account prematurely, I believe their great regard to truth, which has always been the basis of their researches for the improvement of natural knowlege, will require none for this. I shall therefore, as briefly as I can, relate the further experiments, that were made, which evidently demonstrate the error of the former; and from which some phænomena have occurred, perhaps hitherto unknown. In order to try what difference the air passing thro’ a thinner body of water might occasion, I brought the horizontal pipe, which (as mentioned in the former account) was placed 12 inches under the surface of the water, to within six inches; and found, on setting the engine to work, that the leaden pipe, for the conveyance of air from the bellows into the boiler, became much hotter than I had perceived it before; which could not happen, if a constant cool air had passed thro’: and on shutting the cock, which was fixed in the leaden pipe to hinder the steam from ascending into the bellows before the engine should be set to work, tho’ no air could then possibly pass thro’, yet the bellows still continued to move with the same regularity as before; which, on examination, was found defective on the inside, where the middle board, that divides the two bodies, was warped and cracked in several places, thro’ which the air passed very regularly from one body to the other at each stroke, instead of passing thro’ the pipe into the boiler, as imagined. By this, the cause of deception was evident; which I was still in hopes of remedying, by having a new pair of bellows made, somewhat larger, and much stronger. When this was fixed, and the engine worked a few strokes, I was surprised to find the bellows did not come down, but remained fully charged with air, tho’ it had 400 lb. weight upon it; and that, on increasing the weight gradually to 1400 lb. which