1( ; RECORD AND REDUCTION 



0°.l and 0°.2 alternately from the successive daily means. The monthly mean 

 temperature at the hours 4, 8, noon, 4, 8, midnight, was first made out (if dimi- 

 nished by the above constant 0°.I5, their mean would exactly give 19°.55). To 

 obtain the intermediate values for 2, G, 10, A. M. and P. M., the observations be- 

 tween the 21st and 30th were used as follows: — 



Mean temp, at midnightfor last 10 days . . . 12°.30 Same for 30 clays, 11°. 38 

 2 A.M. " " ... 11.85 



Difference . . . — 0.45 



which, applied to 17°.3S, gives 16°. 93; in the same way, we obtain from the fol- 

 lowing hour, 4 A. M., the value 17°. 38. The mean, or 17°. 15, has consequently 

 been adopted as the mean monthly temperature at 2 A. M. The remaining values 

 were derived in a similar manner. 



February, 1858. On the 11th and some following days, there are occasionally 

 pencil figures inserted between the lines. These are neither used nor explained. 



April, 1858. The daily mean from six observations differs from the daily mean 

 from twice this number of observations by 0°.13, as found from the values between 

 the 1st and 17th; a correction of — 0°.13 has, therefore, been applied to the de- 

 duced means on aud after the 18th, in order to refer the same to the result produced 

 by twelve observations. The hourly means at the bottom of the page were ob- 

 tained in the manner explained in the note to the hourly means of the month of 

 September, 1857, viz : through a comparison of the hourly means of the full series, 

 and applying the correction (the mean found from the preceding and following- 

 column) to the monthly mean at the hours 4, S, 12, etc. 



May, 1858. The temperature at 8 A. M. on the 2d was assumed to be 30°.5. 



March. IS 59. The correction to refer the mean from six observations on each 

 of the last four days of the month to the daily mean as resulting from twelve ob- 

 servations, was found by comparison of the respective means on the twelve days 

 preceding; it was found — 0°.1G. The mean hourly temperature for the hours 2, 

 0, 8, 10, was obtained by the process applied on two former occasions. 



April, 1859. The bar in the column for 4'' and in the column for midnight, 

 indicates that the observations were taken one hour later and one hour earlier, or 

 at -V and ll 1 ' respectively. This practice was discontinued on the 5th of July 

 following. 



July, 1859. For the temperatures of the 5th, at the hours 2, 4, 6, 10, A. M., 

 I have adopted the interpolated values 36°, 30°. 5, 39°, 43°, respectively. The 

 correction to refer the mean of six observations (hours 5, 8, noon, 4, 8, 11) to the 

 mean of twelve observations (hours 4, 8, 12, A. M. and P. M.), was derived from 

 the tables constructed for Van Rensselaer and Boothia Felix; the latter value 

 having the weight 2, it was found = — 0°.21, which quantity was applied in the 

 first column of means, July 1st to July -1th inclusive. To obtain the correct 

 hourly means for the month, the numbers in the column for 5 1 ' (first four days) 

 were first referred to the reading at 4 1 ' by subtracting 0.5. The same correction 

 v. ;i applied to refer the readings from 11 P. M. to midnight. The monthly means 

 lor the hours 1. S. 12, A. M. and P. M., being known, the means for the interme- 



