OF B S E II V A 'I' 1 O N S P O II T I'. MI'i; It A T U R K 



L5 



tions at 4 h , 8 h , 12 h , A. M. and P. M., to obtain the daily mean from twenty-four 



observations : — 



Latitude. Longitude. Fahrenheit. 



Boothia Felix . . . 69° 50' 92° 1' 0°.00 



Drontkeim . . . . G3 26 —10 25 —0.09 



Van Rensselaer . . . 78 37 70 53 —0.00 



Lcith 55 5'J — 3 10 +0.06 



Adopted correction ....... — 0.03 



The resulting mean temperature for the month of July, in latitude 02° N. and 

 longitude 39°.l W. is, therefore, 4-45°.56 — 0°.03 = +45°.53, as given in the 

 general table of results. The means for the hours 4, 8, and 12, are derived from 

 the observations between the 6th and the 31st, omitting those on the 19th, and 

 taking 53° for the interpolated value at 4 h A. M. on the Gth. 1 For the sake of 

 uniformity, the quantity -)-l .26 has been added to each of these hourly means, so 

 that the mean of all may again produce 45°. 56. 



The correction to refer the mean from the observations at certain hours of the 

 day to the mean derived from twenty-four readings a day, for the remaining months, 

 has been deduced from the observations at Van Rensselaer Harbor and Boothia 

 Felix. The following table contains these corrections: — 



August, 1S57. The two omissions on the 6th were supplied by 42° and 43°. 



September, 1857. The values for the 21st were interpolated as follows : 2 A. M. 

 12°.0, 6 A. M. 15°.2, and 10 A. M. 21°.2. From the observations between the 21st 

 and 30th, we find that the mean of twelve observations a day is 0°.15 smaller than 

 that derived from six observations a day ; the second column of means between 

 the 1st and 21st, therefore, is derived from the preceding column by subtracting 



The interpolated value for 8 P. M. on the 21st is 38°. 6. 



