METEOROLOGICAL OBSERVATIONS. 



18^ 



The above figures were next referred to standard thermometer No. 3, and further 

 corrected for effect of annual change. The diurnal eft'ect of this change was com- 

 puted by the preceding formula for T, and the daily increase of temperature found 

 as follows : — 



January . 



— 0°.28 



February . 



—0.02 



March 



+ 0.39 



April 



+ 0.77 



May 



+ 0.78 



June 



+ 0.38 



July 



. —0°. 10 



August . 



. —0.36 



September 



. -0.39 



October . 



. —0.39 



November 



. —0.40 



Deceniber 



. —0.38 



for the middle of each month. Without regard to sign, one-half of these quantities 

 will be the correction for 0'' A. M. and 12 P. M. ; at noon there is, of course, no 

 correction, and for the intermediate hours the correction is proportional to the 

 interval from noon ; the A. M. and P. M. corrections at the same hours are the 

 same, but with signs reversed. An examination of the diurnal fluctuation in July, 

 August, and September, at Van Rensselaer Harbor and at Port Kennedy, shows 

 that the August value is quite well represented by a mean of the July and Septem- 

 ber values ; the August value for Port Foulke has consequently been interpolated 

 by means of the two adjacent months. 



Diurnal fluctuation of the temperature. 



(Corrected for errors of graduation of thermometers, and for effect of annual change.) 





A. M. 



P. M. 







11 





2i> 



4 



6 



8 



10 



Hooa. 



2 



4 1 6 



8 



10 



12" 



January . . 



—26.67 



—26.27 



—26° 81 



—25.74 



— 25°.47 



—25°. 24 



—25°. 86 



—26°. 21 



—26.09 



—25°. 84 



—26°. 16 



—26°. 04 



February 







—26.96 



—27.23 



—26.01 



—24.21 



—24.21 



—24.01 



—22.99 



—24.14 



—24.53 



—24.73 



—24.60 



-25.78 



March 







—25.14 



—25.90 



—25.30 



—23.04 



—22.34 



—20.66 



—17.03 



—18.51 



—20.89 



—22.04 



—23.51 



—24.96 



April . 







—13.74 



—14.18 



—12.90 



-11.38 



—10.86 



—9.56 



—8.76 



—9.86 



—10.96 



—11.65 



—13.31 



— 13.S7 



May . 







+20.28 



+22.18 



+23.33 



+25.50 



+26.27 



+26.72 



+26.33+26.01 



+25.58 



+23.67 



+21.98 



+20.74 



.June 







+32.41 



+33.78 



+34.64 



+35.18 



+36.30 



+36.821+37.40+36.85 



+36.23 



4-35.21 



+33.75 



+32.80 



.July . 







+39.48 



+39.80 



+40.15 



+41.68 



+42.52 



+42.261+43.68+43.45 



+42.44 



+41.66 



+41.35 



+ 39.42 



(August) 







+30.58 



+30.92 



+31.21 



H-32.11 



+32.59 



+32.73+33.61+33.46 



+ 32.69 



+32.23 



+31.93 



+30.60 



September 





+21.79 



+22.13 



+22.32 



+22.54 



+22.70 



+23.19+23.51 



+23.43 



+ 22.87 



+22.73 



+22.42 



+21.68 



October . 





+ 6.66 



+6.66 



+6.47 



+ 7.05 



+7.81 



+8.53 +8.80 



+8.77 



+8.40 



+ 8.22 



+7.34 



+ 7.07 



November 





+1.90 



+1.85 



+ 2.82 



+ 2.73 +2.95 



+3.22: +3.29 



+3.70 



+3.97 



+3.67 



+ 3.58 



+2.69: 



December 





—11.56 



—12.84 



—13.00 



—13.41,-12.76 



—12.63—12.48 



—11.50 



—12.65 



—12.57 



—13.23 



—11.89 



If we subtract from each value the respective monthly mean, the residuals will 

 represent the diurnal fluctuation proper, a + sign indicates higher, a — sign lower 

 temperature than the mean of the day. The last two lines show the diurnal 

 fluctuation for Van Rensselaer and Port Kennedy for comparison. 



