MADE AT MARIETTA, OHIO. 



19 



The variation in the annual mean temperature is further exhibited in the annexed 

 diagram (A). 



Diagram A. — Fluctuations of the Mean Annual Temperature during 40 Years. 



T — rn — I — I — r 



•^\ 



+3= 

 +2 

 +1 

 

 — 1 



-2 



-3 L-L 



1 — i — I — i — i — I — I — i — i — i — I — I — I — I — 1 — I — I — r 



\ 



/ 



-I — I — 1 I I I L. 



/-\ 



J I I 1 I I I L. 



Ot-i{MCOT}lioCDl>OOOiOi-H(M 



cNco-^in^Dt^ooosOfHcqco-^m^t^oo 



Irregular Flvxituations of the Temperature as Exhibited in the Monthly Means. 



The irregular variations of the temperature may be shown by comparison of the 

 mean temperature on each day with its normal temperature found from the 31 years 

 of record, or it may be determined, for each month, by comparison of each monthly 

 mean with the corresponding mean from the whole series, and using the formula 



£;= 1.2533 — we secure the advantage of an expression of the mean deviation of 

 any monthly mean value. The mean deviation of a monthly value is as foUows: — 



January 



February 



March . 



April 



May 



June 



+ 5°.04 

 6.02 

 4.49 

 3.87 

 2.87 

 2.90 



July +2°.32 



August 2.32 



September .... 2.76 



October 2.95 



November . . . . 3.66 



December .... 4.48 



The irregular fluctuations of the temperature are therefore greatest in February 

 and least in July and August, the ratio is nearly 2.6 to 1. 



The irregular fluctuations may also be exhibited by the extreme values in the 

 monthly means, for each month, during a series of years ; for Marietta the lowest 

 and highest means are as foUows : — 





Lowest. 



Highest 



January 



. 18°.61 



41°. 68 



February 



. 20.65 



43.88 



March . 



. 28.15 



51.87 



April . 



. 42.56 



61.31 



May 



. 55.43 



69.17 



June 



. 65.23 



74.22 





Lowest. 



Highest. 



July . 



. 69°.84 



77°.19 



August . 



. 67.30 



75.95 



September 



. 57.18 



70.28 



October . 



. 45.53 



58.21 



November 



. 36.11 



49.54 



December 



. 20.49 



43.72 



