one-tenth of an inch. Then fprinkle, or fift the filings of iron through gauze, fo that they may fall gently near the equator of the magnet. You will immediately fee the filings to divide ; one part moving with an accelerated velocity to the north pole, the other part to the fouth pole, each approaching as near to its refpectivé pole as the interpofing fluid will permit; each turning and prefenting a diffimilar pole to that which firft put the particle in motion. As other particles fucceed in their turn, the fame effects take place; each endeavours to approach as near to its pole, as its centre, as poffible; but the particles already arrived preventing an approach within the limits thus previoufly occupied, the whole are neceffarily arranged in the form of concentric circles. Particles of water in forming drops, or of mercury in forming globules, obey nearly the fame law. Thus doth this experiment unequivocally demonftrate, from the motions of the floating particles, that attraction is the fole caufe of this phænomenon, and that this force is equally exerted by each pole. It fhews, at the fame time, that each of the filings, even the fmalleft, becomes itself a magnet fo foon as it arrives within a fhort diftance of its attracting pole. This is particularly evinced by thofe particles which are firft put in motion, and which Occupy the nearest stations. For, immediately upon their arrival at a certain diftance, they turn round, and prefent to the magnet their oppofite extremity. Experiment II. Place two diffimilar ends of magnets about an inch apart, in a large difh; let them be juft covered with water, fift the Elings between the ends. The par ticles of iron are immediately attracted by the nearest pole; they move quickly in oppofite directions, occupy the neareft ftation they can, become themfelves magnetic, and prefent to each other diffimilar poles. The particles attracted by the poles of the magnet thus mu tually attract each other. Between the poles of the large magnets, thefilings are arranged in ftraight lines; because there they tend directly to the attracting points; the more removed, the more curvilineal their pofition; because each particle making the fame effort to occupy the neareft ftation to the centre of attraction, they are all neceffarily forced into a pofition correfponding with that effort. Experiment III. Place fimilar ends of two magnets, as the diffimilar were fituated in the laft experiment, and fift the filings bes tween them. Here alfo you fee them to be acted upon by attraction as before; they move to the nearest pole, become magnetic, and prefent to each other fimilar poles; that is,' fappofing the north poles of two magnets to be oppofed, all thofe filings which are attracted by the north pole of one of the magnets prefent a north pole to the north pole of all thofe attracted by the other magnet; they repel each other, of confequence; a vacuity is obferved between the refpective parcels of filings; whilft the appearance of reverted curves is exhibited, on account of the repulfion which their fimilar poles exert upon each other. Thus, befides the proof which thefe experiments afford, that the attractive force of the magnets, at either pole, is the real caufe of the phænoinena which the filings exhibit, they prove alfo, in the most fatisfactory manner, that the action of the magnet upon the filings, when they approach within a certain diftance, renders them magnetic, and hence produces the effects mentioned in the two laft experiments. But, in every inftance, attraction firft operates. Similar poles, whilft they are repulfive of each other, are fill attractive of all other fubflances upon which the magnet acts. The fame body, at the fame time, appears to exert two oppofite powers. The caufe of magnetic attraction and repulfion as well of all other attractions or repulfions, lies ftill hid in the recetles of nature; but the manner, in which thefe forces produce certain phænomena, is no longer concealed from us. Thefe experiments may be agreeably varied by placing three or four magnets upon each other, then covering them only partially, and fprinkling the filings on each fide of them. In every magnet there is at least one line, called the equator, where the attractive power vanithes: from this line, towards either pole, it gradually increafes, and hence thofe filings which are near to the fides of the magnet will incline towards them, forming angles, which appear to be fuch as the revolution of the two forces, one ateral, the other polar, would neceffarily produce. Perhaps this method of making experiments, by fabilances floating in water, and thus fubjected in all their motions to our examination, may lead to more important difcoveries. The rates in which the magnetic attractive force decreafes, at different diftarces, may, I think, be collected from noting the velocity with which the floating bodies move, at different diftances from the poles, or the spaces, which they pafs over in equal times. Nothing obftructs an accurate folution of this problem but the difficulty of obtaining measurements of fufficiently fmall intervals of time. If the experiment were made upon a large fcale, the difficulty might be removed. The remarkable acceleration which is obfervable, when the filings come near to their attracting point, feems to fatisfy the eye, that the attraction increases in a greater ratio than according to any law yet affigned. One magnet acts upon another, at a confiderable diftance, either by repulsion or attraction. Will not thefe experiments lead to a rational conjecture, that in every inftance the action is communicated by intervening magnetic fubftances? It acts through atmospheric air. But this air may, from its conftituent principles, and it is faid does, contain iron. The fmall particles floating in the atmosphere may be acted upon like thofe floating upon water. The tenuity of the particles will only render the action more fenfible. Each may become a magnet, and thus, by the action of all the intervening affected particles, the action of one magnet may be communicated to the poles of another diftant magnet. I have made an experiment, in order to afcertain whether a magnet could exert its power in a Torricellian vacuum. A fmall quantity of filings was poured into a glafs tube, of fufficient length; it was then filled with mercury, and inverted in the fame fluid; the filings floated on the furface of the mercury in the upper end. The refult was, that the action of the magnet upon the fi lings, at equal diftances, was fenfibly lefs than when the tube was full of atmospheric air. The want of a tube of fufficient diameter prevented me from making the experiment in fo fatisfactory a manner as I wished. It appears, however, worthy of being repeated by thofe who may poffels the neceffary means. If the magnetic power fhould be obferved in fuch a vacuum, then the above conjecture will merit and receive the fate which has generally attended all reafoning in phyfics not founded on accurate experi ment. Experiment in making Ilay, by Mr. Arthur Young. From the Annals of Agriculture. FTER a series of warm and a violent rain fell on the 30th. On going to my farm, I found my bailiff had loft that feafon for hay, in common with all his neighbours, and had begun to mow but the day before the rain. At vol. XXVIII. p. 543, of the Annals,' there is an account, by Mr. Barclay, of a new mode of making hay, that of mowing only when the grafs is quite dry, and cocking it immediately: but that fyftem I had before found! much difapproved by the workmen, and with fome realon-grals never mows fo well as when wet, and if very dry, will not cut fo clofe as it ought to be mown. I therefore, on this oc cafion, tried the experiment of making the hay by a lyftem of cocking, but without reftraining the fcythes on account of rain. From July firft to the eighteenth, no day paffed without rain; there was, however, time enough dry to form the fwaths foon after mowing into (mail grafs cocks, which were left two days, turned and thaked up a third, put three together the fifth, turning thefe and thaking up the feventh, again the tenth; the fourteenth day opened the cocks for an hour and put them in rows, and then cocked. them in larger cocks, This was the fucceffion of the work; and on the fixteenth day from mowing it had taken no hurt, though rain had fallen every day, and heavily in fome. Of course the times varied in different fields, and in parts of the fame field; but this was the mode purfued with the whole. On St. Swithin's day, the. fifteenth, it rained moft heavily, and again on the fixteenth and feven. teenth but the bailiff on the seventeenth, there being an hour or two of bright weather, broke and laid into beds about three acres, but was beat out by rain, and the hay left exposed. It rained on the eighteenth, but fine weather, fufficient to dry, cart, and flack, fet in on the nineteenth. About one-fourth ft its colour, and was falted in ftacking; the reft, though damaged, was good, and much better than it would have been in the common method of making. ANTIQUITIES. ANTIQUITIES. Defcription of Richborough-Cafle. outfide, is 38 feet; of the wet From Pennant's Journey to the Ife of Wight. R ICHBOROUGH caftle ftands in the parish of Afb, on the eaft fide of the village, on the edge of a lofty flope, once washed by the fea: at prefent the Stour paffes beneath its base. The form is rectangular. Moft of the walls, remain; are very thick, ftrong, and lofty; and the cement now fo hard as to baffle the efforts of thofe who have lately endeavoured to deftroy them. The materials are great pebbles, flint, chalk, &c. bedded in the mortar, which confifts of lime, fea fhells, broken tile, and small pebbles. The pieces of chalk were taken by the Romans from the foot of the adjacent cliffs, and have the pholades remaining entire in their cylindrical cells. The whole was faced with, fquare ftones, perhaps Purbeck, and, as ufual, had tiers of tiles at certain distances, two tiles thick: the fquare fcaffold holes remain. The foundation of the wall is pitfand, flint, chalk, twice repeated, flints lodged in mortar, and laftly, a ftratum of mortar. The thickness at the bafe is eleven feet three inches, but at the height of a few feet, ten feet eight inches. The length of the fouth wall, on the wall, 490 feet; of the north wall, 560 feet. The north wall, in its most perfect part, is about 25 feet high; it ran down the flope, towards the fea, and reverted for the pace of about 190 feet along a natural terrace, and ceafed where the terrace ceafed, and the bank became inacceffible. Vaft fragments of the wall are fallen down the flope. The weft entrance is laid with large fquared ftones, ftratum fuper ftratum. Near this place, in the northweft corner of the caftle are found frags of flags horns fawed off: boars tufks; oifter fhells in abundance; and the exuviæ of other animals: the whole area is confiderably above the external ground, and confifts of rubbish interfperfed with thin layers of mortar. In the north wall, on the outfide, is the foundation of a fquare tower, and there are marks of four more in different parts of the walls. Their fituation is pointed out by a particular arrangement of round holes lined fmoothly with mortar penetrating many feet into the fubftance of the wall, but no where pervading it. The porta decumana is beneath a tower in the north wall, through which the entrance into the cattle is in an oblique direction. In the area of the caftle has been lately difcovered a platform of fold mafonry, mafonary, in form of a parallelogram, the fides of which are 144 feet by 104; the depth five feet. It is a compofition of large flint ftones and courte mortar. On its furface are remains of a fupertiructure in the fhape of a crofs, (which has been faced with the fquared ftones,) rifing fomewhat above the ground, and more than five feet above the platform. A wharf, or landing place, was difcovered fome years ago in the plain at the foot of the flope about forty roods northward of the castle, about four feet high, of a triangular form, one of the fides parallel with the bank, and its oppofite angle projecting towards the fea; the fides were nearly equal, of about ten feet each. It was a fhell of brick work, two bricks thick, filled with earth, the two projecting fides tied together with a brace of the fame material, Two forts of brick were used in this building; one was 18 inches by 12, and three inches and a half thick; the other 17 by 11, and one and a quarter thick. Mr. Ebenezer Muffel, of BethnalGreen, near London, purchafed the whole quantity of materials, and employed them in paving a court yard, and part of his houfe. The amphitheatre lay on the north fide its form is deffroyed, but the vaft hollow marks the place. Multitudes of antiquities have been difcovered in and about the caftle; fuch as uns, coins, fragments of earthern ware, marble mouldings, and brazen figures of Mercury, and of a bagpiper. The laft represents a foldier armed in his helmet playing on the bagpipe, with the pipe in his mouth, and the bag, which is very large, placed almoft before him, and preffed with both armis. I have in my voyage to the Hebrides, p 317, given a full hif tory of the ufe of this inftrument at different periods. Richborough has a moft advantageous profpect, which might be one reafon for fixing on this fitua tion It commands all the way from the North to the South Foreland, and all the harbour in which it flood, fo that no fleet or vellel could elcape its oblervation. Account of an Entertainment given by the Society of Lincoln's Inn, to Charles II. and his Court. From Ireland's picturesque Views, and hiftorical Account of the Inns of Court of London and Westminfier. IN N the fteward's office is the admiffion book, from 1671 to 1673, containing the following curious account of a vifit paid to Lincoln's Inn, by Charles II. and his court. As it tends to difplay the hofpitality of that period, I have inferted it at length. What adds to the curiofity of this account is, that the king and nobility prefent entered their names with their own hands; and, if we may judge from the appearance of the writing, many of them, and particularly Killigrew, the jester;' were a little non compos mentis. "A narrative of the kings majefties reception and entertainment att Lincolnes Inne, the nyne and twen tieth day of February, 1671." "Sir Francis Goodericke, knight, one of his majefties learned councel att law, and folicitor generall to his royal highneffe the duke of Yorke, being reader of this fociety of Lincolnes Inn for the Lent reading, in the year 1671, having invited the |