58 



MEMOIRS or THE NATIONAL ACADEMY OF SCIENCES. 



age, ami tliat nt l.oO p. in., after its close, it was O.S below. Interpolating from these values the 

 diftcrences which would probably have existed at the time of the eclipse had there been no 

 unusual phenomenon, we have the values of the effect of the eclipse given in tlie last column 

 under the heading " Depression." 



AIR TEMPERATURE. 



Tlie maximum depression of temperature was therefore only about 4°, but this was sufficient 

 to reduce the temperature to a value 0^.1 lower than it had been at 7.00 a. m. on the same day; and 

 Qo.G lower than it was at 9.00 p. m. 



HUMIDITY. 



The effect of the eclipse upon the humidity may be found by comparing the psychrometric 

 readings taken during the progress of the eclipse with tliose of other days. The following table 

 gives the result of this comparison, the values iu the column lieaded "average" being deduced 

 from the mean values from April 25 through May 5, omittiug May 4. Tlie " regular decrease for 

 the day " is interpolated from the observed differences at 9.57 a. m. and 2.00 p. m. : 



RELATIVE HUMIDITY. 



The above table indicates an increase iu the relative humidity during the eclip.se, reaching ^'w 

 jjer cent. 



