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[Vol. IV., No. 99. 



changes of temperature. 1 A rough measure of the 

 average daily range for summer and winter is seen 

 in the vertical lines drawn through the July and 

 January dots : these are commonly longer in sum- 

 mer than in winter. The hottest and coldest rec- 

 ords for every month are marked by A and V. 



SINGAPORE 

 -100 



• T- * -■■' 



KEY WEST 



NEW ORLEANS 



AAA 



( VUMA ^ A * 



* A 



..." 



^Cht 



-ao 



v v f 



vC' ': 



<■ v * 0- 



S T MICHEL 



-100 FRANCE. 



' y 1 ,: 



BOSTON 



A 



A < 



ST VINCENT 



\ 



VAKUTSK 40 . 

 sibcria 



A 



/ \ 

 / k~ 





* 



A /" "v 



-0 



*60 



..''"'' 





~~ 



^ ^ V V . 



« 



w 



V V 



v V 



•V V — 



-60 v 



DENVER 

 -100 A A 



SAN FRANCISCO . 



.SITKA 



A 



7 . K A ,.. +s 



- PIKE'S PEAK 



V 1 



-0 



- V . W v 

 It 



-40 i - 



- j- . - , v v » - 



_ v v * 



• •••■•»..../ v 





- 





V v 





V 



Denver is thus seen to be warmer but more vari- 

 able than Pike's Peak. In San Francisco the sum- 

 mer heat extremes rise higher above the mean 



1 The variation of monthly means for Boston is large, in compari- 

 son with that of the other diagrams, partly because it is taken from a 

 thirty-five year record instead of from the eleven or fewer years of 

 the signal-service reports. 



curve than the winter colds fall below it, while the 

 reverse is the case with New Orleans. The ex- 

 treme variation between winter minimum and sum- 

 mer maximum, even of different years, is only 23 

 F. at Singapore : our least variable station is Key 

 West, with a maximum change of 53 F. Yuma, 



Arizona, although 

 well known as often 

 excessively hot, con- 

 fines its variations 

 within 93 ; Denver 

 has a recorded 

 change of 134 from 

 105 to — 29 ; while 

 Fort Benton, Mon- 

 tana, leads the list 

 with a change of 

 167 , between 108 

 and — 59 , but even 

 this is exceeded at 

 Yakutsk. The con- 

 trast between east- 

 ern and western 

 coasts is seen in the 

 variability of Boston 

 as compared with St. 

 Michel, on the coast 

 of France in about 

 the same latitude, 

 the latter being 

 warmer and less 

 variable because it 

 lies to the leeward 

 of a temperate ocean, 

 while Boston is to 

 leeward of an un- 

 tempered land; and 

 again in comparing 

 Boston (in latitude 

 42 21') with Sitka 

 (in latitude 57 3'), 

 and recognizing the 

 small difference in 

 their mean tempera- 

 tures, and the de- 

 cided decrease in 

 variability, annual and diurnal, in going from the 

 east coast to the west. The effect of going inland 

 is to increase changes of temperature ; for, while the 

 sea is conservative of its warmth or cold, the land 

 allows great and rapid variations. If the climatic 

 zones had been first named in this country, ours, 

 would never have been called the ' temperate.' 



