SOLAli ECLIPSE, MAY 0, 1SS;5. 



513 



WIND. 



TIio pieseut eclipse funiisljcd au unu.sually favorable opportunity for determining any ductua- 

 tions that might occur in the direction and velocity of the wind caused by the eclipse. The 

 regularity of the wind from day to day, both in direction and velocity, made it possible to obtain 

 a reliable basis of comjjarison. Observations were made every live minutes from 10.00 a. m. to 

 1.15 p. m., with the result that no appreciable change was detected cither in direction or force. 

 The wind blew with almost the same velocity from the eastward during the period of time occupied 

 by the eclipse. The following table gives the ob.served velocity in miles for every ten miimtcs 

 from 10.00 a. m. to 1.30 p. m. : 



The mean ten-minute velocity from 7.00 a. m to 9.00 p. m. is exactly the same, viz, 1.38 miles. 

 The observations on other days show the following relation between the velocities from 10.00 

 a. m. to 2.00 p. m., and those from 7.00 a. m. to 9.00 p. m.: 



Mean wind velocity for each ten minutes. 



Meau of April 20, 27, 29, 30, May 1, 5, when the bourly velocity was greater than 6 miles is +0.11. 



Judging from these comparisons it might have been expected that the wind would blow 

 somewhat stronger between the hours of 10.00 a. m. and 2.00 p. m. than during the rest of the day. 

 On the contrary, the observed velocity was the same. Con.sequently, if the passage of the moon's 

 shadow had any effect at all on the velocity of the wind, it was to slightly diminish it. 



DIUKNAL VARIATION IN THE VELOCITY OF THE SOUTHEAST TRADE-WIND. 



The series of observations with the anemometer on Caroline I-sland is not snfBciently exten- 

 sive to indicate any diurnal periodicity in the wind velocity. During the voyage from Callao, 

 however, the Hartford sailed day after day in the region of the southeast trades upon almost the 

 same parallel of latitude, and with but few changes in the positions of the sails, no steam being 

 used. The conditions were so constant during the interval of twenty-two days from March 23 to 

 April 13, in which the vessel sailed in latitude — lio.o from longitude 79° to 137°, that it was 



