i METEOROLOGY. 313 



j Ic. — For Jefferson Barracks, Mo., p. 625, latitude 38^°, 



(The mean of 22 years is 55° 46 



I The mean of 3 hours, 11 years is 56°. 42 



I The mean of 4 hours, 11 years is 55°. 77 



i In all these only whole years are introduced, while in the annual 

 I means of tlie Consolidated Tables, parts of years are sometimes intro- 

 duced, which will account for a slight discrepancy to be noticed in 

 some of the results. 



The conclusion from the above results is that the observations at the 

 three hours, and at the four, give close approximations. 



To all this add the assertion of Dr. Coolidge, j)reviously mentioned, 

 which led to a return to the hours of 7 a. m,, 2 and 9 p. m., at the 

 Military Posts. At these three hours also, the observations under 

 the direction of the Smithsonian Institution are made over the country. 



These are convenient hours for recording observations over our ex- 

 tensive country, and the results need only slight correction, according 

 to the publications in the Toronto Observations, and still less accord- 

 ing to the data already detailed. 



From the observations of 1839 at Amherst College, and the results 

 communicated by Prof. Snell, I have deduced the following table of 

 corrections. Their object is to give the monthly mean, and hence 

 the annual mean of twenty-four daily observations, by applying the 

 numbers in the table, to the monthly mean at any hour, according to 

 their sijjns: 



