BOOK II. xLviii. 128-130 



that ceases beginning. When those next to the ones 

 falling rise, they go round from left to right " like 

 the sun. The fourth moon usually decides about the 

 course of the winds for the month.* Vessels by 

 means of slacking sheets can sail in contrary direc- 

 tions with the same winds, so that collisions occur, 

 usually at night, between ships on opposite tacks. 

 The South wind causes larger waves than the North- 

 east because the former being below blows from the 

 bottom of the sea but the latter from the top ; 

 consequently earthquakes following South winds are 

 specially destructive. The South ^\and is more 

 violent at night and the North-east wind in the day- 

 time ; and easterly winds continue longer than 

 westerly. North M^nds usually stop after blowing an 

 odd number of days, an observation that holds good 

 in many other departments of nature also : this is 

 why the odd numbers are thought to be masculine. 

 The sun both increases and reduces the force of the 

 wind — the former when rising and setting, the latter 

 at midday in summer seasons ; consequently the 

 winds are usually lulled at midday or midnight, 

 because either excessive cold or excessive heat makes 

 them slack. Also winds are lulled by rain ; but they 

 are most to be expected from quarters where the 

 clouds have broken, reveaHng a clear sky. 



Eudoxus however thinks that (if we choose to 

 study the minimal circuits) there is a regular re- 

 currence of all phenomena — not only of Avinds but 

 largely of other sorts of bad weather as well — in 

 four-yearly periods, and that the period always 

 begins in a leap-year at the rising of Sirius. 



These are our observations vvith regard to the 

 winds that are regular. 



269 



