| XXX | (500) | XXX |
500 ASTRO The Tide-Dial, PlateL. fig. i. The outfide parts of this machine confift of, i. An eight-fided box, on the top of whichat the corners is flrewn the phafes of the moon at die octants, quarters, and full. Within thefe is a circle of 29! equal parts, which are the d y£ of the moon’s age accounted from the fun at new moon, round to the fun again. Within this circle is one of 24 hours divided into their refpeQive halves and quarters. 2. A moving elliptical plate, painted blue, to reprefent the rifing of the tides under and oppofite to the moon ; and has the words, high <vja:er, tide falling, low water, tide rifing, marked upon it. To one end of this plate is fixed the moon M by the wire IV, and goes along with- in 3. Above this elliptical plate is a round one, with the points of the compafs upon it, and alfo the names of above 200 places in the large machine (but only 32 in the figure, to avoid confufion) fet over thofe points in which the moon bears when fhe raifes the tides to the greateft heights at thefe places twice in every lunar day: And to the north and fouth points of this plate are fixed two indexes / and K, which Ihew the times of high water, in the hour circle, at all thefe places. 4. Below the elliptical plate are four fmall plates, two of which proj'edt out from below its ends at new and full moon ; and fo, by lengthening the ellipfe, fhew the fpring-tides, which are then raifed to the greateft heights by the united attraflions of the fun and moon. The other two of thefe fmall plates appear at low water when the moon is in her quadratures, or at the fides of the elliptic plate, to fhew the neap-tides; the fun and moon then afting crofs-wife to each other. When any two of thefe fmall plates appear, the other two are hid; and when the moon is in her o&ants, they all difappear, their being neither fpring nor neap-tides at thofe times. Within "the box are a few wheels for performing thefe motions by the handle or winch H. Turn the handle until the moon M comes to any given day of her age in the circle of 294- equal, parts, and the moon’s wire IV will cut the time of her coming to the meridian on that day, in the hour circle; the XII under the fun being mid-day, and the oppofite XII midnight : Then looking for the name of any given place on the round plate (which makes 29-4 rotations whilft the moon M makes only one revolution from the fun to AST ASTROP-WELLS, in Northamptonfhire, were recommended by the phyficians Willis and Clever, for the cure of the fcurvy, afthma, 6^. ASTROSCOPE, an inftrument compofed of two canes, having the conftellations delineated on their furfaces, whereby the ftars may be eafily known. ASTRUM, with chemifts, fignifies that virtue which accrues to things from their preparation; and among ancient phyficians, certain medicines in the figure of round cakes impreffed “with afterifks. ASTUR, in ornithology, a fynonime of a fpecies of falco. See Falco. ASTURIA, a maritime province of Spain, lying along
N O M Y. the fun again) turn the handle till that place comes to. the word high water under the moon, and the index which falls among the forenoon hours will Ihew the time of high water at that place in the forenoon of the given day : then turn the plate half round, till the fame place comes to the oppofite high-water mark, and the index will Ihew the time of high water in the afternoon at that place. And thus, as all the different places co».»e fucceflively under and oppofite to the moon, the indexes fliew the times of high water at them in both parts of the day: And, when the fame places come to the lowwater marks, the indexes (hew the times of low water. For about three days before and after, the times of new and full moon, the two fmall plates come out a little way from below the high-water marks on the elliptical plate, to (hew that the tides rife ftill higher about thefe times: And abcut the quarters, the other two plates come out a ’ittle from under the low-water marks towards the lun, and on the oppofite fide, (hewing that the tides of flood rife not then fo high, nor do the tides of ebb fall fo low, as at other times. By pulling the handle a little way outward, it is difengaged from the wheel-work, and then the upper plate may be turned round quickly by hand, fo as. the moon may be brought to any given day of her age in about a quarter of a minute ; and by puffing in the handle, it takes hold of the wheel-work again. On AB, (fig. 2 ) the axis of the handle H, is an endlefs fcrew C, which turns the wheel FED of 24 teeth round in . 4 revolutions of the handle: This wheel turns another ONG of 48 teeth, and on its axis is the pinion P§>_ of four leaves, which turns the wheel LKI of 59 teeth round in 294 turnings or rotations of the wheel FED, or in 708 revolutions of the handle, which is the number of hours in a fynodical revolution of the moon. The round plate, with the names of places upon it, is fixed "on the axis of the wheel FED; and the elliptical or tide-plate with the moon fixed to it, is upon the axis of the wheel LKI; confequently, the former makes 294 revolutions in the time that the latter makes one. The whole wheel FED, with the endlefs fcrew C, and dotted part of the axis of the handle AB, together with the dotted part of the wheel ONG, lie hid below the large wheel LKI. A S Y the bay of Bifcay, with Gallicia on the weft, and Bifcay on the eaft. It gives the .title of prince to the elded fon of the king of Spain. ASTYNOMI, in Grecian antiquity, magiftrates in Athens, correfponding to the tediles of the Romans; they were ten in number. See Aldile. ASYLUM, a fan&uary, or place of refuge, where criminals ffelter themfelves from the hands of juftice. The afyla of altars and temples were very ancient; and likewife thofe of tombs, ftatues, and other monuments of confiderable perfonages: Thus, the temple of Diana at Ephefus was a refuge for debtors, the tomb of Thefeus for (laves. The Jews had their
