AST 



AST 



there was a golden circle of 365 cubits in circiiniference, and 

 one cHibic thick, divided into 365 equal parts, according to 

 the days of the year, and containing the heliacal rifings and 

 fettings of the ilars for each d?.y, &c. See Heliacal. 



It is evident, indeed, without placing much reliance upon 

 thefe accounts, that botti Chaldsea and Egypt were coun- 

 tries extremely proper for sftronomical oblcrratioiis, being 

 almcil conllantly favoured with a pure atmofplierc and a fe- 

 rene Iky ; and whatever may be thought of the lower cf 

 Belus, or the circle of Ofymandyas, we cannot but foim a 

 very advantageous opinion of the knov.ledge of the Egvp. 

 tians in pradical aftrononiy, from the pofition which they 

 Lave given to their pyramids, whofe faces are direftcd with 

 great precifion towards the four cardinal points of the com- 

 pafs. For as it is fcarcely pofiible that a fituaticn fo exaft 

 could have been the effeft of chance, we mull conclude 

 that they were acquainted with a corredl method of draw- 

 ing a meridian line ; which io a matter of more difficulty 

 than is ufually thought ; it being well known that Tycho 

 Bralie, the moft. able aftronomer of his time, committed an 

 error of fevcral minutes in tracing that of his obfervatory 

 of Uraniburg. See Meridian. 



The Chaldaeans alfo mull have made very confiderable 

 advances in this fcience, if we can rely upon the teftimony 

 of Simplicius, who informs us that, at the taking of Baby- 

 lon by Alexander the Great, they cited a regular feries of 

 allronoinical obfervations for 1903 years back ; and that 

 thefe, through the means of Callillhencs, were afterwards 

 communicated to the Greeks by Ariftotle. But it is much 

 to be wiilicd that the truth of thefe ancient obfervations 

 was better eilabhilied, particularly as their hillorian Bcrofus, 

 who appears to have lived but a little before the time of 

 Alexander, makes no mention of any aftronomical monu- 

 ment of this people, which was more than about 480 years 

 anterior to that period. And, indeed, the moil ancient 

 Chaldsan obfervations, of which any mention is made by 

 aftronomical writers, are thofe of three eclipfes of the moon, 

 employed by Ptolemy in his Almageft, which were made in 

 the years 27 and 28 of the oera of NabonalTar, or 721 

 and 720 years before Chrift. 



But though Ptolemy, and perhaps Hipparchus, from 

 whom he had probably taken them, made no ufe of any 

 obfervations more ancient than thofe here mentioned, we 

 cannot from thence conclude that the Chaldeans firft began 

 to follow the celcftial motions at this period. For fuch as 

 were made in much earlier times might be fufpeiled on fe- 

 vcral accounts ; and it is befidcs highly probable that moll 

 of thofe which preceded the xra of Nabonaflar were not 

 accompanied with .dates fufficiently accurate to be employed 

 by thefe aftronomers. The Babylonian calendar, before 

 this xra, was in great confuilon, not having been properly 

 regulated ; and it is obvious that ancient obfervations, ei- 

 ther of this or any fimilar kind, can be but of little ufe, 

 except we are able to afcertain the precife time at which 

 they were made. 



Bcfides thefe eclipfes mentioned by Ptolemy, nothing 

 more now remains of the Chaldaean aftronomy, except what 

 is attributed to them by fomc ancient authors, with refpetk 

 to certain periods of years, which they appear to have formed 

 fur the more ready computation of the places of the hea- 

 venly bodies. And though the accounts which have been 

 given us of one of the mofl remarkable of thefe cycles, by 

 isuidas and Pliny, are not wholly free from objcilions, there 

 can be little doubt of its having bceji firll invented by that 

 people. This is the celebrated period called the Chaldxan Sa- 

 ros, which confills of 223 lunar montlis, or a little more than 

 iSi years ; and which fo far agrees with the combined mo- 



VOL. Ill, » 



tlone of the fun and moon, as always to bring them agT.iil 

 into nearly the f;ime pofition at the end of each cycle that 

 they had at its commencement. 



Both the Chaldeans and Egyptians, indeed, fre gere- 

 rally fuppofed to have pofTelfid a vcrv confiderable ki.ow- 

 Icdge of ftveral other branches of this fcience bcfides thofe 

 here mentioned ; but for want of proper authorities, this 

 can only be judged of by feme juft notions which they 

 appear to have had of the fyftem of the world, and by 

 the agreement v.hich has been found among fevcral ancient 

 meafures of the circumference of tlie earth. The Eg)'p- 

 tians, in particular, appear to have known, long before the 

 Chriftian asra, that the year confided of 365! days, and that 

 the planets Mercury and Venus moved round the fun. Wk 

 are alio well affured of the great antiquity of tlie fcience 

 among this people, from the recent difcoveries which have 

 been made in that country during the late war ; and parti- 

 cularly from the figure of a zodiac brought from thence by 

 the French, which Lalande coiifidcrs as extremely ancient. 



But ainong the various nations which claim the honour of 

 having hrft cultivated this fcience, none pretend to poHefs 

 obfervations of greater antiquity than the'Chinefe. The 

 moll remarkable of thefe is a conjun£lion of five of the 

 planets, which, according to their annals, is faid to have 

 taken place in the rcignof their emperor Tchuen-hiu, about 

 2500 years before Chriil. They alfo mention an eclipfe of 

 the fun, which happened in the conllcllation Scorpio, about 

 the \ear 2150 of the fame ajia ; and which is faid to have 

 proved fatal to two Chinefe aftronomersof the names of Ho 

 and Hi, who were condemned to death by the emperor 

 Tehong-kang, ' on account of their omitting, througK 

 negligence and intoxication, to announce the precife time 

 -nt which it arrived. And from thefe data, apparent'y well 

 attefted, feveral eminent aftronomers have endeavoured to 

 difcover whether thefe events could licive poffibly happened 

 about the time here mentioned ; but the fubjeft is attended 

 with too many difficulties to afford any fatisfaClory refult. 



All that we know of the Chinefe aftronomy is from the 

 accounts which have been given of it by the Jefuit mifiiona- 

 rics, who are much divided in their opinions with rtfpecl to it* 

 very great antiquity ; fome fuppoling it to have flouriflied 

 at a more earlier period than othys. F. Du Halde, how- 

 ever, afferts, that it was cultivated by their great lawgiver 

 Confucius; and that Tcheou-cong, the moll flcilful aftro- 

 nomer that China ever produced, lived more than loco 

 years before Chrift, and paffed whole nights in obfer\-irg 

 the celellial bodies, and arranging them into conftellations. 

 But whatever might have been the knowledge of this peo- 

 ple in former times, the Rate of aftronomy is very low in 

 that countiy at prcfent, although it is cultivated at Peking 

 by public authority, in the fame manner as in moft of the 

 capital cities of Europe. 



The inhabitar.ts of Japan, Siam, and the Mogul's empire, 

 alfo appear to have been acquainted with aftronomy from 

 time immemorial ; and the famous obfervatoiy at Benares 

 (fee Observatory) is a monument both of the great in- 

 genuity of the Indians, and of their (kill in that fcience. 

 A knowledge of this fubjcA is alfo fuppofed to have pre- 

 vailed among the Americans; though, 111 their divifions of 

 time, they made ufe of the folar and not of the lunar 

 motions. The Mexicans, in particular, are faid to have 

 difcovered a fingular prediletlion for the number 1 3, which 

 they ufed as a kind of cycle in moft ot their co;rpiitations. 

 And the abbe Clavigero afferts it as a remarkable facl, 

 that having difcovered the excefs of a few hours in the 

 folar above the lunar year, they made ufe of intcroa! -•■r 

 days to bring thera to an equality, as was done by Juli.j 

 Y Cii.ir 



