useful lessons. In some years the changes of the weather seem to be much influenced by the moon's place in the Zodiac; that is, when the moon passes the equinoxial line, or when she returns from her greatest declinations South or North; but a register of the weather, kept constantly for some years, assures me, that there is no dependence on these circumstances. Í could never discover any cause to which I could impute the regularity of the changes in the weather; but can assure the attentive husbandman, that there is, in some years, a remarkable regularity in them, and in all years some degree of regularity. This regularity in the changes of the weather, is most conspicuous in the intermediate months between the equinoxes, that is, during May, June, July, and August, in summer; and, during November, December, January, and February, in winter. The knowledge of the most probable times of these changes may be of great use in agriculture, as well as to seafaring men. Let me here mention some other circumstances in regard to the barometer. The rising of the mercury forebodes fair weather, and its falling portends rain, with winds. During strong winds, though unaccompanied with rain, the mercury is lowest. Other things equal, the mercury is higher in cold than in warm weather. In general, we may expect, that when the mercury rises high, a few days of fair weather may be expected. If the mercury falls in two or three days, but soon rises high, without much rain, we may expect fair weather for several days; and in this case, the clearest days are after the mercury begins to fall. In like manner, if the mercury falls very low, with much rain, rises soon, but falls again in a day or two, with rain, a continuance of bad weather may be feared. If the second fall does not bring much rain, but the mercury rises gradually pretty high, it prognosticates good weather of some continuance. When the mercury rises high, the air sucks up or dissolves into its own substance the moisture on the surface of the earth, even though the sky be overcast. This is a sure sign. of fair weather; but if the earth continues moist, and water stands in hollow places, no trust should be put in the clearest sky; for in this case it is deceitful. Very heavy thunder-storms happen without sensibly affecting the barometer; and in this case the storm seldom reaches far; but when attended with a fall of the barometer, it reaches much more extensively. In all places nearly on a level with the sea, rain may be expected when the quicksilver falls below thirty inches. This points out one cause of the more frequent rains in lofty situations than in low open countries. Thus double the quantity of rain falls at Townly-hall, in Lancashire, than does in London, as we are informed in the Transactions of the Royal Society. The heights of the quicksilver in the barometer above referred to, hold only in places on a level with the sea; for experiments have taught us, that the mercury falls considerably in inland places, according to their heights. As your Magazine is perused by many of the most ingenious men in the kingdom, I wish they were called on to account for that power in the air of occasionally dissolving water, if I may so express it, and of mixing the water with itself (as salt is in water) generally invisible, and at other times in vapours, which soon form clouds. Winds, especially from dry continents, have great power of thus raising water. Evaporation, by means of the sun's heat, is generally mentioned as the efficient cause; but whoever attends to the quantity of snow, and even of ice, that is carried off into the air, in the most severe frosts, will be convinced that heat is not the principal cause. The quantity of water thus raised into the air may be estimated by numerous springs which owe their source to vapours thus raised. The waters of these springs uniting form the greatest rivers. Add to these, the quantity that fall in dews and rain, which give birth to all vegetables, and to that beautiful verdure which gives a peculiar beauty to this country, in the enjoyment of which, other nations envy us. As we are ignorant of the cause of this power in the air, of dissolving water, so are we no less ignorant whence it is that the air occasionally drops these vapours in dews, rains, &c. 1789, April. LI. Experiments in Natural Philosophy. MR. URBAN, AGRICOLA AN account of a loaf loaded with quicksilver being thrown into water to discover the body of a person sunk under the surface, which could only become stationary (if it did so} from attraction, encouraged me to offer the following, in hopes that some one may improve upon the hint: Being under the Cliff at Scarborough, I observed two persons looking very earnestly at the different oozings of the water that dribbled down the sides, and tasting the moisture by dipping in their fingers. I went to them, and found them Germans. They were very obliging; and, as I understood the language, informed me they were very well versed in searching after mines, which by thus tasting the water they could discover. I mentioned what I had heard of the divining rod, in use on the Mendip Hills, in Somersetshire, which bends when held over places that contain metallic ore; they said that might well be, for a piece of gold, silver, or any metal, suspended on the end of a very slender switch, when carried over a mine of the same metal, would be so attracted as to bend the end of the stick, Some time after, I happened to be at a silversmith's at Bath, who had a very curious pair of scales, inclosed in a glass case. I admired them; and he said they would weigh to the 200th part of a grain; and there lay in the window a block of solid silver, about six inches square and two inches thick. What the abovementioned persons told me at Scarborough, came into my head, and I thought this a good opportunity to try how far what they said was true. I, therefore, had a shilling put into one scale, and the beam, which was about 18 inches long, made perfectly level by weights in the other scale; then I introduced the block of silver under the scale that had the shilling, and the beam dropped at that end a full quarter of an inch, and stood there until the block of silver was removed, when it immediately returned to the equipoize and level it was before: and this we repeated several times, and it always answered the same. These curious scales were inclosed in the glass case, and the door shut, at every experiment. The other matter, I think, may be made useful for keeping metal pipes or boilers from the furring, or stony excressence, that lodges from boiling water often in them. A friend of mine at Rochester put a common flat shell of an oyster into a new tea-kettle, and kept it in two or three years. During all the time the shell was in the tea-kettle, the tea-kettle gathered no fur, but all the furring settled on the oyster shell, which I have in my possession now, and which is about two inches thick, and something bigger than it was when put in, and perfectly smooth at the bottom, and where at the edge it had from time to time slipped against the side of the tea-kettle, in appearance like a hone you set razors on; but on the top of the shell the fur was like any thing boiling up, curly and uneven. The water there comes from chalky lands. I live in Essex, and have tried the shell, which also gathered the fur, but of a different appearance, being more like smooth sand or gravel; but the shell increased in thickness. If this can be turned to account, in respect to keeping boilers and pipes clear, or shewing the nature of the land through which the streams have passed, I shall be happy. 1791, March H. INDEX TO THE SECOND VOLUME. A. ABRAXAS, 41. Accents, Dissertation on, 385. Acta Diurna, 1. Adages, Greek and Latin, 162, 199. Adam, his beard, 293;-his voice, 294. Addison, on Paradise Lost, 360, 368;-his observation on Virgil's Achates, 378. Enigma, antiquity of the, 40. Ajax, the silence of, in the infernal shades, 164, Albumazar, comment on the old play of, 98. Allegories in ancient history accounted for, 95. Analogy of language, remarks on, 173, note. An't please the pigs, 88. Antiquities, Roman, discovered, 454, Arabian Tales, on the authenticity of, 382. Aristophanes, 328. Articles, on the promiscuous use of, 333. Assassin, origin of the word, 146, Astle on Writing, 281. Atherton Cliffs, natural curiosities found at, 458, |