NUMBER OF THE FIXED STARS. 145 



more frequently conceal stars visible to the naked eye. If the 

 calculation of occultations of the stars were extended to those 

 of the 9th magnitude, a stellar eclipse would, according to 

 Galle, occur on an average every 44' 30", for in this period 

 the moon traverses a portion of the heavens equal in extent to 

 its own surface. It is singular that Pliny, who was undoubtedly 

 acquainted with Hipparchus's catalogue of stars, and who 

 comments on his boldness in attempting as it were " to leave 

 heaven as a heritage to posterity," should have enumerated 

 only 1 600 stars visible in the fine sky of Italy ! * In this 

 enumeration he had, however, descended to stars of the 5th, 

 whilst half a century later Ptolemy indicated only 1025 stars 

 down to the 6th magnitude. 



Since it has ceased to be the custom to class the fixed stars 

 merely according to the constellations to which they belong, and 

 they have been catalogued according to determinations of place, 

 that is, in their relations to the great circles of the equator or the 

 ecliptic, the extension as well as the accuracy of star catalogues 

 has advanced with the progress of science and the improved 



6 " Patrocinatur vastitas cccli, immensa discreta altitudine, in 

 duo atque septuaginta signa. HOBC sunt rerum et animantium 

 effigies, in quas digessere coclum periti. In his quidem mille 

 sexcentas adnotavere Stellas, insignes videlicet effectu visuve" 

 . . . . Plin.,ii. 41. " Hipparchus nunquam satis laudatus, ut 

 quo nemo magis approbaverit cognationem cumhomine siderum 

 animasque nostras partem esse coeli, novam stellam et aliam 

 in cevo suo genitam deprehendit, ej usque motu, qua die fulsit, 

 ad dubitationem est adductus, anne hoc saipius fieret move- 

 renturque et erc quas putamus affixas ; itemque ausus rem 

 etiam Deo improbam, adnumerare posteris Stellas ac sidera ad 

 nomen expungere, organis excogitatis, per qua? singularum 

 loca atque magnitudines signaret, ut facile discerni posset ex 

 eo, non modo an obirent nascerenturve, sed an omnino aliqua 

 transirent moverenturve, item an crescerent minuerenturque, 

 ccelo in hereditate cunctis relicto, si quisquam qui cretionem 

 earn caperet inventus esset." Plin., ii. 26. 



VOL. III. L 



