AST 



AST 



ASTROBOLISM, derived from «-•.-;, _/?.if, and ISm.!j, 

 I Jh'de, tliL- fame with fihacdu! ; ihougli properly applied 

 to plants wliicli arc dellroyed in the do^-days, as if 

 blafttd hv thnt ftar. 



ASTRODICTICUM, an aftronomical iiiftrmnent in- 

 vented by M. Weiglielii'.s, by means of wliicli many perfons 

 (liall Ik- able at the fame time to behold the fame liar. 



ASTROGNOiSlA, from ^;-r.;,JIar, and ytt^nx, I Inow ; 

 the art of knowing the fixed itars, their names, ranks, iitu- 

 ations in the conftellations, and the like. 



ASTROITES, in Natural Hijlory, a fpecies of M.'.dre- 

 roRA found in the feas of South America. The flars are 

 numerous, immerfcd, and have the diHc concavo-cylindrical. 

 'This is madrepora (radians) aggregata folida, llellis confertis 

 convexiufculis, centri poro radiante, llriis Icabriufculis of 

 Pallar- ; and allrca apertnris cavernarum minimis maffa in- 

 aquali of Brown's Nat. Hift. Jam. It is found in large 

 maffes ; and is of a whitifli colour. I'he interlliccs are 

 porous. 



ASTROLABE, derived from arr:, Jl.-.r, and >.x/^,?:-.vi,-, 

 / tale, alluding to its nfe in obferving the ftars ; and by 

 the Arabs called j-ijlhar-hib, formed by corruption from the 

 common Greek name ; was originally ufed for a fyllcni or 

 alTemblage of the fcvcral circles of the fphere, in their pro- 

 per order and fitiiation with rcfpctl to each other: and the 

 ancient allrolabes appear to have been mucli the lame with 

 our aiTuiliary fphcres. 



Tlie full and mod celebrated of this kind was that of 

 Hipparchus, which he made at Alexandria, the capital of 

 E"ypt, and lodged in a fecure place, wheie it Icrved for 

 divers aftronomical operations. Ptolemy made the fame 

 ufe of it ; but as the inftrument had feveral inconveniences, 

 he contrived to change its figure, though perfedlly natural, 

 7.nd agreeable to the doftrine of the fphere ; and to reduce 

 the whole aftrolabe upon a plain furfaee, to which he gave 

 ihe denomination of the planifphere. — Hence 



Astrolabe is ufed among the moderns for a planifphere ; 

 •or a ftereographic projection of the circles of the fphere upon 

 the plane of fonie great circle thereof. 



The ufual planes of projedion are that of the equinoflial, 

 the eye being fuppofed in the pole of the world ; that ot 

 the meridian, the eye being fuppofed in the point of inter- 

 feftion of the equinoflial and horizon ; and that of the 

 horizon. 



Stofflcr, Gemma Frifins, and Clavius, have treated at 

 large of the allrolabe. — For a farther account of t'.ie nature 

 and kinds thereof, fee Planispheri;. 



Astrolabe, or Sea j'lflnlnbe, more particularly denotes 

 an inftrument chiefly tifed for taking the altitude of the pole, 

 the fun, or ftars, at fea. 



The common aftrolabe, reprefented Plate Navigation, 

 Jig-i- coniiftsof a large brals ring about fifteen inchesin diame- 

 ter, wliofe limb, or a convenient part therof, is divided into 

 degrees and minutes ; fitted with a moveable index or label, 

 which turns upon the centre, and carries two figlits. — At 

 the zenith is a ring A, to hang it by, in time of obfeiva- 

 tion. 



To ufe the aftrolabe, tm-n it fo to tire fun as that the 

 rays may pafs freely thro'.igli botii the fights F and G, in 

 which cafe the edge of the label cuts the altitude in the di- 

 vided limb. 



The aftrolabe, though now difnfed, is efteomed by many 

 equattoany of the otlier inllruments ufed for taking the alti- 

 tude at fea ;. cfpccially between the tropics, when tl'.e fun 

 comes near the zenith. — There are a prcat many other iifes of 

 the aftrolabe ; on which Clavius, Hcilrion, i^c. have written 

 entire volumes. 



ASTROLOGICAL Fate. See Fatf. 

 ASTRO LOGl'E, m Idihyolugv, the French name of 

 the fpecies of Uranoscopus calLd joponkiis by Gmelin, 

 from its inliabiting the feas about fapan. 



ASTROLOGY, the art of foretelling future events, 

 from the ai'pects, pofitions, and influences of the heavenly 

 bodies. 



The word is compounded of arrf,Jla>; and >';\o:, iVifeourfe ; 

 whence, in th.c literal fer.fe of the term, aftrology flunild fig- 

 nify no more than th.e dodiine or fcicnce ot the ftars ; which, 

 indeed, was its original acceptation, and formed the ancient 

 aftrology ; though, in courfe of time, an alteration has 

 arifen ; that which the ancients called aftrology, being 

 afterwards termed Astronomy. 



Aftrology may be divided into two branches, natural and 

 judiciary. 



To the former belongs the predicting of natural efiefts ; 

 as, the changes of weather, winds, ftorms, hurricanes, thun- 

 der, floods, earthquakes, &c. This art properly belongs 

 to Physiology, or natural phihjophy ; and is only to be 

 deduced a ■pojlcrior'i, from phenomena and obfcrvalions. Its 

 foundation and merits the reader may gather from what we 

 have faid under Air, Atmosphere, and Weather. For 

 this aftrology, Mr. Boyle makes an apology, in his Iliftory 

 of the Air. 



AsTROLony, Judk'iavf ox yudldal, which is whatwccom- 

 monly call fimple aftrology, is that which pretends to fore- 

 tell moral events ; i. e. fuch as have a dependence on the free 

 will and agency of man ; as if they were dirctlcd by the liars. 

 This art, which owed its origin to the pradice of knavery 

 on credulity, and which the celebrated Mr. Briggs denomi- 

 nated a mere fvftem of groundleis conceits (Ward's Lives, 

 p. I2(^.), is now univetfally exploded by the intelligent part 

 of mankind. There was a time, however, wlien this fcience, 

 frivolous and ridiculous as it may be juilly denominated, 

 furniflicd very powerful incentives to the ftndy of ailronomy. 

 Wit'iout fome knowledge of the motions and af]ie£ts of the 

 ftars, the al'rologers would have been unable to draw their 

 horoicopes, and of courfe to read the fates of men in the 

 face of the heavens. Accordingly, Kepler obfeives (Pnef. 

 ad Rudolph. Tab. p. 4.), " that aftrology isthefoolifli daugh- 

 ter of a wile mother, and that, for 100 years paft, this wife 

 mother could not have lived without the help of her foolilb 

 daughter." " I repent bitterly,'' fays Kepler, " having fo 

 much dcer'ed aft'-oli-gy ;" and he conceived that the ftudy 

 of ailronomy had been greatly negleclcd, ever fince men 

 ci.akd to apply themfclves to aftrology. Of the origin of 

 this abfurd and unfounded Icie-ice, whatever might be the 

 relative eftimation in wiiieh it was held, it is not difficult to 

 give a phu'fible account. When heroes, and peifons who 

 by extraordinary Icrvices had rendered their names venerable 

 and immortal, received divinehonours, iomeparlicular celcllial 

 bodies, of which the fun, moon, and other planets feemtd 

 to be the moll fuitable, were affigned to theie divinities ; 

 and after this appropriation, folly, which nevers ftops where 

 it begins, proceeded ftill farther, and afcnbed to them the 

 attributes and powers tor which the deities, after whom 

 they were named, had been celebrated in the fiftions of the 

 mvthologirts. This, in proccls of time, laid the foundation 

 ot aftrology ; and hence the planet Mars, for inllance, like 

 the deity of that name, was laid to caufe and to be fond of 

 v.ar, and Venus to prefide over love and its pleafures. 



The profelfors ot th's kind of aftrology maintain, " That 

 the heavens are one great. volume or book, wherein God has 

 written the hiftoiy of the world ; and in which every man 

 may read his own fortune, and the tranfaclions of his time. 

 — The art, they fay, had its rife f;om the fame hands as 



ailronomy 



