36 



RESULTS OF METEOROLOGICAL OBSERVATIONS 



this temperature difference was considerably greater than during 

 it should be, from physical considerations. 



days of snow, as 



Mean Annual Temperature and Secular Change. 



The mean annual temperature of a place is one of the principal meteorological 

 constants to be determined ; by means of these values the annual isothermal lines 

 may be drawn and the important question of a secular or periodical change may be 

 investigated. 



The annual means in Table VIII are made out directly from Table III ; they are 

 the average values of the monthly means. The few blanks in Table III were sup- 

 plied by the substitution of the respective average monthly mean, as given at the 

 bottom of the table ; the annual mean was then taken as usual. The average for 

 the year 1853 was obtained by interpolation from 8 months of observation at Fort 

 Preble, and comparing the same with the monthly means from 22 years of observa- 

 tions as given in the Army Meteorological Register. The average for 1853 is but 

 an approximate value. 





Table VIII- 



-Observed Annual Mean Temperature 



at Brunswick, Me. 





Tear. 







1 



2 



.3 



4 



i 



6 



7 



8 



9 



1800 











. - . 



... 









- . . 



43°. 66 



43°.43 



42°.14 



1810 



43°. 57 



44°. 71 



40°. 94 



43°.18 



43°.29 



42''.87 



42°.09 



41.64 



44.78 



45.46 



1820 



44.03 



43.91 



43.06 



41.03 



43.86 



45.73 



45.46 



43.87 



46.94 



46.19 



1830 



47.50 



47.66 



45.17 



45.61 



45.36 



44.42 



43.00 



49.60 



50.69 



51.45 



1840 



51.60 



46.58 



45.84 



43.87 



42.32 



43.27 



44.01 



43.08 



43.70 



43.00 



1850 



43.37 



42.60 



43.91 



44.53 



42.73 



42.95 



41.78 



43.62 



43.75 



40.31 



The mean temperature from 52 years of observation is 4-4°. 40 Fahr. according to 

 the above table ; reduced to the level of the sea it becomes 44°.60 nearly. The 

 lowest observed annual mean, 40°.31, occurred in 1859, and the highest observed 

 annual mean, 51°. 60, occurred in 1840; range 11°.29, which is rather larger than 

 the usual amount. 



The numbers in Table IX are obtained by subtracting the average annual tem- 

 perature from the mean of each year ; a positive sign indicates a temperature above 

 the normal value, a negative sign the reverse. 



Table IX. — Fluctuation op the Annual Mean Temperature. 



Tear. 







1 



2 



3 



4 



s 



6 



7 



8 



9 



1800 

 1810 

 1820 

 1830 

 1840 

 1850 



— .83 



— .37 

 +3.10 

 +7.20 

 —1.03 



+ '.81 

 — .49 

 +3.26 

 +2.18 

 —1.80 



—3.46 

 —1.24 



+ .77 

 + 1.44 

 — .49 



—1.22 

 —3.37 

 + 1.21 

 — .53 

 + .13 



—1.11 



— .54 

 + .96 

 —2.08 

 —1.67 



—1.63 

 +1.33 

 + .02 

 —1.13 

 —1.45 



—2.31 

 +1.06 

 —1.40 

 — .39 

 —2.62 



— .74 



—2.76 



— .53 

 +5.20 

 —1.32 



— .78 



— .97 

 + .38 

 +2.54 

 +6.29 



— .70 



— .65 



—2.26 

 +1.06 

 +1.79 

 +7.05 

 —1.40 

 —4.09 



These numbers show the usual irregular fluctuations, though on a somewhat 

 enlarged scale. A rough comparison with a number of other stations, treated in 

 the same way and taken from the Army Meteorological Register, indicate a general 

 conformity of the march of the annual mean temperatures, excepting, however, the 



