METEOROLOGY. 



413 



FOURTH CLASS— Continued. 



FIFTH CLASS. 



Cases of a more or less clouded sky (cloudiness exceeding 2) connected 



ivith brisk winds. 



The cases of this class, being very numerous and of a more uniform 

 character, it is not deemed necessary to give them here in detail. 

 Mean difference of temperature 0°.5. 



BEST HOURS FOR OBSERVATIONS OF TEMPERATURE. 



BY PROF. C. DEWEY, LL. D. 



The meteorological and physical tables published by the Smithsonian 

 Institution contain much additional proof of the close approximation 

 derived from the daily observations of the temperature at 7 a. m, and 

 2 and 9 p. m., to the actual mean of the day, month, and especially 

 year. 



Presuming this evidence must be highly gratifying to the observers 

 over our country, I have selected the following from the Smithsonian 

 tables, or made the calculations from them for their gratification. 



The following is the list of the places, their latitude, and the reduc- 

 tion for mean temperature at the hours of 7, 2, and 9, and for the one 

 fourth of the sum of the observations at 7 a. m., 2 p. in., and 2 (9 p. m.) 

 Inspection shows how very small is the reduction for the last: 



