laxatives not operating. A clyfter was given, and the laxative again repeated. Next morning, his left arm and leg were quite paralytic, the pupil of the left eye was dilated, and did not contract when a lighted candle was brought near it, nor was he sensible of its being there; but he could read distinctly with the other eye, and the right leg and arm were very well. In the afternoon, just forty-eight hours from the time that he met with the accident, the bone was laid bare, and in the middle of the right parietal bone, a piece was found to be broken off more than an inch fquare. The upper fide had pierced the dura mater, and gone into the substance of the cerebrum. The broken piece was easily taken out, and the wound dreffed. Immediately after, the pupil of the left eye contracted, and he could diftinguish large objects with that eye, and the leg and arm were lefs affected. He had a good night, and next morning could read when the right eye was shut. On the third day after the operation, when the wound in the dura mater inflamed, and a confiderable tumefaction came on, his left eye, leg and arm became again paralytic, with frequent convulfions in the left leg and arm, but without the smallest complaint in the other side. In this state, he continued for feveral days; a fuppuration came on; the fwelling went off; after which he continued well, and the wound healed up in eight weeks. FROM these cases, I should infer : I. THAT when one hemifphere of the brain is affected, it generally produces its morbid fymptoms on the oppofite fide of the body. 2. THAT when both hemifpheres are affected, the whole body fuffers. 3. THAT though one hemifphere only is affected, when the injury is great, the whole body will suffer. 4. THAT 4. THAT though the cerebrum alone is hurt, it produces morbid fymptoms in all muscles of voluntary motion, whether their nerves take their rife immediately from the cerebrum, from the cerebellum, or from the medulla oblongata. 5. THAT, in cafes of external accident, where one fide is affected, it is more favourable than when both fides fuffer. V. V. EXPERIMENTS on the EXPANSIVE FORCE of FREEZ ING WATER, made by Major EDWARD WILLIAMS of SIR, TH [Read by Mr ROBISON, Nov. 6. 1786.] HE following is an extract of a letter to me from Major EDWARD WILLIAMS, of the Royal Artillery, a learned man, and of great profeffional merit. Being at Quebec in fome very cold winters, among various other ingenious experiments, it occurred to him to try the force of congelation in fome of the iron bomb-shells, which are ufually fired out of mortars in the practice of artillery; by filling the cavity of the shell with water, and then, having plugged up the fuze-hole, expofing it to the cold to freeze the water, in order to find whether the expansion of the ice would be capable of bursting the shell. THE dimensions of the 13 inch shell are as follow: Outer diameter of the fhell, Inner, or diameter of the cavity, Diameter of the fuze-hole, And the dimensions are fimilar in the other fhells. Inches. 12.8 9.r 1.5 2.2 1.7 The fuze hole is conical, the oppofite fides of which, when produced, meet meet at the extremity of the diameter, which paffes through. the middle of the hole. HE found, that the iron plug could hardly ever be driven fo firmly into the fuze-hole as to refift the force of the expanfion of the ice, which pushed it out with great velocity, and a bolt or cylinder of ice, of a confiderable length, immediately shot up from the hole. But when the plug was fixed in with springs, which laid hold of the infide of the cavity, fo that the plug could not poffibly be pushed out, the force of expansion then split the shell, and a fin or plate of ice fhot out quite around. EXTRACT from Major WILLIAM's Letter. THESE experiments were made on iron-fhells, from the 13 inch-fhell to the coehorn, of 4.4 inches diameter, by filling the fhell nearly with water, and driving in an iron plug with a fledge hammer. Dec. 21.-THE fuze-axis of the fhell lay nearly perpendicular to the horizon. On examining the effect, about 9 o'clock the following day, I obferved the plug gone, and a cylinder of ice, of 4 inches high, rising perpendicularly from the fuzehole, and of equal diameter. I fearched carefully for the plug, but but could not find it, as there was about 3 feet of fnow on the ground. 22.-I WATCHED this fhell about an hour, when, being called out on business, I found, on my return, three hours after, the plug gone, and the icy cylinder 24 inches high. Plug loft. 23.—I HAD a plug made, and jagged or notched along the fides, to prevent its being forced out fo eafily; and watched this shell for upwards of three hours, going into the house at intervals to warm myself. The last time I went in was about half an hour after twelve, when, after a few minutes, I heard a fort of hiffing found, upon which running out, the plug was gone, and a cylinder of ice fhot up, exceeding any of the former, being 6 inches high. Plug loft. 24. A SIMILAR plug to the laft. I watched this with more success; for although absent at intervals; yet at half past four in the afternoon, (therm. at 6°) I saw the plug fuddenly forced out by the column of ice, accompanied by the hiffing noise; and, obferving its fall, I found it at 62 feet from the fhell. The icy cylinder was 4-inches high, and the fuze-axis of the shell I found lay nearly at an angle of 80° with the horizon. 31.-CONCLUDING from the foregoing experiments, that no plug could be fo fixed, as to render the resistance at the fuzehole greater than at the weakest part of the fhell, in which cafe I supposed it would burst, (which was the primary object in these experiments) I thought it might be worth while to obferve how far the force of congelation would project a plug of a given weight and figure, and forced in with the fame number of strokes of the fledge hammer. For this purpose, I placed the fuze-axis of the fhell at an angle of 45° with the horizon, and on the 31st of December 1784, being the coldest day of this year, the plug was projected whilst I was abfent, a cylinder was shot out, in the direction of the axis, of 7 inches, and not inVOL. II. clining d |