METEOROLOGICAL OBSERVATIONS. 



181 



The average representation of the mean temperature of any one month is +2°. 4, 

 and of the mean annual temperature +0°.'7. According to the above formula the 

 warmest day is July 15th, temperature +41°.6, and the coldest day February 16th, 

 temperature, — 28°.0. The annual mean temperature is reached on April 22d, and 

 November 14th. On the annexed diagram the curve represents the computed 

 annual fluctuation, and the dots the observed mean monthly temperatures. 



Anhual Fluctuation op the Tempekatube op the Aik at Pokt Foulke. 



+460 



(Middle of each, month.) 



The monthly range, that is, the difference of the highest and lowest mean 

 "temperature of any day of the month, is greatest in November (41°), and least in 

 July (19°). 



The lowest temperature recorded (and corrected for index error) was — 45°.4 on 

 January 25th, 1861, 6 A. M., and the highest temperature recorded was +61°.0 on 

 July 5th, 1861, 2 P. M. On the 28th of July, 1861, at Cape Isabella, in nearly the 

 same latitude as Port Foulke, the temperature rose to +63°. at 10 A.M.; the 

 vessel was then among the floe ice.^ The extreme range of temperature experienced 

 was therefore 108°.4 of Fahrenheit's scale ; at Van Rensselaer Harbor the extreme 

 range was 117°.4, and at Port Kennedy 104°.8. 



The diff'erence in temperature of the atmosphere at Port Foulke and Van Rensse- 

 laer Harbor, due to the cause stated in the mtroduction to the meteorological part, 



» The minima thermometers (159T and 1639) were exposed too late in the winter (March 1st) to 

 record the lowest temperature. The maxima thermometers (1T05 and 165T) recorded +6'7°.0 June 

 22d; but the two instruments differed then 8° in their indications, and their errors of graduation 

 were not determined. No. 1G51 broke July 2d, and No. 1T05 was not read after July 12, 1861. 



