TABLES OF DIFFERENCES OF MEAN TEMPERATURES. 155 



Group IV. Four stations in Mass., 



Conn., and N. Y. <|,^ = 41°.7 ;i^ = 72°.6. More than 4 years. 



t = 4- 4S°.65 + 6°.27 sin(0 + 232°.7) + 1°.38 sin(2 + 61°.l) 

 + 0.10 sin (3 + 359°). 



Group V. Three stations in Penn. 



and Dist. of Col. ^„ = 39°.6 1^ == 75°.8. 15 years. 



t = + 53°.38 + 6°.55 sin(0 + 22S°.7) + 1°.27 sin (2 + 48°.l) 

 4- 0.35 sin (3 9 + 36°). 



Group VI. Two Gulf stations. ^„ = 27°.4 X,„ = 84°.9. 2 years. 



t = + 73°.44 + 2°.75 sin(0 + 227°.8) + 0°.70 sin (2 + 57°.5) 

 + 0.17 sin (3 + 31°). 



The hourly means from which these expressions were derived are contained in 

 the following table : — 



Observed Daily fluctuation of temperature, on the yearly average, for groups of stations. 





I. 



n. 



HI. 



IV. 



V. 



VI. 





I. 



II. 



III. 



IV. 



V. 



VI. 



X 





1 





■3 





S 





-6 





13 





Hour. 



Van Rensselaer 

 Port Foulke. 

 Port Kennedy. 

 Boothia Felix. 



en 



Montreal. 

 Thunder Bay li 

 Toronto. 

 Mohawk. 



1 Cambridge. 

 Amherst. 

 New Haven. 

 Brooklyn. 



< .2 =■ 

 III 





Hour. 



Van Rensselaer 

 Port Foulke. 

 Port Kennedy. 

 Boothia Felix. 





Montreal. 

 Thunder Bay I 

 Toronto. 

 Mohawk. 



Cambridge. 

 Amherst. 

 New Haven. 

 Brooklyn. 



<!.2 c 



<2 S .S 

 111 







^ 



^ 



, g 



Q 



Q 









3 

















(, 



Midn't 



—1.8 



—2.4 



—2.9 



—3-9 



-3-8 



—1-5 



Noon 



+ 2.0 



+3-7 



+4.2 



+6.1 



+5-6 



+2.4 



I 



I 



9 



—2.7 



—3-4 



—4 



4 



—4 



4 



—1.8 



I 



+2.2 



+4.0 



+ 5 







+7 







+6 



7 



+2.9 



2 



2 



o 



—2.9 



—4.0 



— S 







—4 



9 



— 2.0 



2 



+2-3 



+3-9 



+5 



6 



+7 



3 



+ 7 



4 



+3-1 



3 



4 





8 



—2.9 

 — 3-0 



—4.4 

 -4.8 



— 5 



4 



—5 

 —6 



5 

 



— 2.2 



3 

 4 



+2.0 

 + 1.6 



+3-5 

 +2.9 



+ 5 

 + 5 



7 



+6 



9 



+ 7 



4 



+3' 



I 



6 



—5 



7 



—2.4 





+5 



8 



+6 



8 



+2.9 



5 



I 



4 



—2.9 



—4.9 



—5 



8 



—6 



2 



—2.8 



5 



+ 1.2 



+2.1 



+4 



3 



+4 



3 



+5 



4 



+2.3 



6 



1 



o 



—2.4 



—4.4 



—5 



3 



—5 



7 



—2.8 



6 



+0.7 



+ 1.2 



+3 



I 



+2 



5 



+3 



5 



+ 1-3 



7 



O 



S 



—1-7 



—3-4 



—4 







—4 



3 



— 2.2 



7 



+0.2 



+0.3 



+ 1 



5 



+0 



9 



+ 1 



7 



+0.3 



8 



+0 



I 



—0.6 



—1.9 



— 2 







— 2 



2 



— I.I 



8 



— 0-3 



-0-5 



+0 



2 



— 



4 



— 



2 



— 0.2 



9 



+0 



7 



+0.7 



—0.4 



+0 



4 











+0.1 



9 



—0.7 



— 1.2 



— 



8 



— I 



5 



— I 



5 



—0.5 



to 



+1 





+ 1.8 



+ 1-4 



+2 



5 



+2 



2 



+1.1 



ID 



— I.I 



—1-7 



— I 



6 



— 2 



4 



— 2 



5 -0.8 1 



II 



+ 1.6 



+2.9 



+2.8 



+4.7 



+4-1 



+ I.S 



II 



—1-5 



2. 1 



— 2.2 



—3-2 



-" =1 



At several stations, interpolation, graphical or analytical, was required to com- 

 plete the hourly values before they could be combined into groups. Frankford 

 Arsenal and Philadelphia values were united into a mean and then combined with 

 the Washington values. 



By means of the equations we readily find the following times of greatest, least, 

 and average heat of the day and of the daily range, on the yearly average. 



