HISTORY OF CHRONOLOGY, 761 



have been a very difficult matter to ascertain with sufficient correct- 

 ness. But to mark and fix the time of the sun's apparent revolution 

 through the heavens among the stars was a matter of so great diffi- 

 culty that it was not exactly ascertained even at the time of the refor- 

 mation of the calendar in 1582 ; yet so uniform is the motion of the 

 earth in its orbit that the results of modern experiments render it 

 next to absolutely certain that the time of orbital revolution has never 

 varied even the fraction of a second. In the infancy of astronomy, 

 many ingenious expedients were adopted to ascertain this and other 

 matters connected with the times and motions of the planets and other 

 heavenly bodies, one of which may be mentioned even at the risk of 

 tediousness. To ascertain the exact time of the revolution of the con- 

 cave of the heavens, two vessels were placed over each other, the upper 

 filled with water, the lower empty. At the moment of the appearing 

 of a certain star above the horizon, the water was permitted to flow 

 from the upper into the lower vessel, and the flow was continued until 

 the same star appeared the next night, when the flow was stopped. The 

 whole concave of the heavens had then made one revolution. The 

 water which had flowed out during this time was then divided into 

 twelve equal parts, and smaller vessels were made each to hold just one 

 of those parts, and on the following evening they repeated the operation, 

 filling successively six of those vessels, and noting carefully what stars 

 rose above the horizon during the time required to fill each of them. 

 Each group of stars which rose during the time of filling one small ves- 

 sel was called a statioti or house of the sun. They then postponed oper- 

 ations upon the other half of the heavens for six months, when they 

 repeated it, and thus divided the path of the sun through the whole 

 heavens into twelve divisions, to most of which they gave the names of 

 certain animals : hence the term zodiac, the propriety of which could 

 have been seen only by the fertile fancies of the childhood of the race. 

 The whole ancient method of dividing and naming the constellations 

 is to us utterly absurd, and is really a hindrance to a knowledge of the 

 stars. Fanciful forms of snakes and dogs and lions and bulls and 

 w^agons and scorpions convey to us no idea but one of confusion and 

 perplexity, and they are tolerated for the same reasons that we tolerate 

 our bungling orthography : we are loath to break away from the 

 associations of antiquity ; we are loath to sever the giabt strides of 

 Science, in its strength and manhood, from the feeble totterings of its 

 infancy. 



The time required by the sun to pass through one of these groups 

 or signs is nearly equal to a lunar month ; the time required to pass 

 through three of them was called a season, as we have it now. All 

 this was done by the Chaldeans or Egyptians, centuries before Greece 

 or Rome had inhabitants or a name. 



The Greeks divided the year into twelve lunar months, but, as this 

 lunar year differed from the true year by about eleven days, they cor- 



