18 



RESULTS OF METEOROLOGICAL OBSERVATIONS 





1 1 



2 



3 



4 



6 



6 



V 



8 



9 



1810 









- - 



. . 



_ . 



. . 



. _ 



53° .45 



54^07 



1820 



53°.07 



51°.61 



54°. 09 



51°.86 



- - 



- - 



54°.07 



54°.25 



65.38 



52.33 



1830 



54.67 



50.36 



52.66 



53.04 



53°.39 



50^.54 



50.43 



51.28 



50.57 



52.42 



1840 



52.27 



52.05 



52.39 



50.38 



52.84 



52.16 



.54.03 



51.62 



52.28 



51.85 



1850 



52.07 



52.33 



52.20 



52.61 



53.96 



52.84 



49.71 



50.84 



53.44 



52.93 



Mean annual temperature from 40 years of observation 52°.46 Fahr. . "Warmest 

 year 1828, coldest year 1856, difference in the mean temperature for these years 

 5°.67, which is comparatively a small range of variation. 



If we subtract the mean value 52°. 46 from each annual mean, we obtain the fol- 

 lowing table of annual excesses ( + ) and annual defects ( — ). 









1 



2 



3 



4 



s 



6 



7 



8 



9 



1810 

 1820 

 1830 

 1840 

 1850 



+0°.61 

 +2.21 

 —0.19 

 —0.39 



— 0°.85 

 —2.10 

 —0.41 

 —0.13 



+1°.63 

 +0.20 

 —0.07 

 —0.26 



— 0°.60 

 +0.58 

 —2.08 

 +0.15 



+0°.93 

 +0.38 

 +1.50 



— 1°.92 

 —0.30 

 +0.38 



+1°.61 

 —2.03 

 +1.57 

 —2.75 



+1°.76 

 —1.18 

 —0.84 

 +0.38 



+0°.99 



+2.92 

 —1.89 

 —0.18 

 +0.98 



+1°.61 

 —0.13 

 —0.04 

 —0.61 

 +0.47 



To obtain a measure of the variability of the annual mean temperature we may^ 

 with sufficient precision, employ the formula^ e = 1.2533 ^^ where A = difference 



of each mean from the mean of the whole series ; [ ] indicates summation irrespec- 

 tive of sign ; ti = number of years, and e == mean error or mean deviation ; in a 

 short series n — 1 might be substituted for 7i. The formula supposes the positive 

 and negative differences to balance. 



Accordingly the mean deviation of any annual mean = ± 1°.25. Dividing this 

 by v/« we find the mean uncertainty of the final annual temperature 52.°46 to be 

 ± 0°.20. 



If we add the differences of the first 20 years we find the annual temperature 

 0°.2 higher, and if we add those of the last 20 years the annual temperature 0°.l 

 nearly, lower than the mean, indicating no change in the climate as measured by 

 the annual temperature between 1818 and 1859. -To ascertain whether the sum- 

 mer and winter temperatures also have remained unchanged the following com- 

 parison is added : — 



Mean Monthly Temperatuke. 





1818 to 1840. 



1840 to 1859. 





1818 to 1840. 



1840 to 1859. 



December 



. 33°.38 



33°.79 



June 



. 70°. 14 



69°.02 



January 



. 31.38 



31.43 



July . 



. 73.40 



73.10 



February 



. 33.91 



34.08 



August . 



. 72.03 



71.06 



Mean 



The differences 0°.14 in winter and 0°.80 in summer are too small, and fuUy 

 covered by their probable uncertainty to draw any other inference than that of an 

 unchanged temperature of the seasons. 



* See Chauvenet's Manual of Spherical and Practical Astronomy, Vol. II, p. 496. Philadelphia, 

 1863. 



