356 ACCOUNT OF THE AECTIC REGIONS. 



to December, follow a similar ratio in almost every 

 maritime situation. 



Considering, then, the mean temperature of the 

 year to be indicated by that of the27th-28tli of April, 

 I have collated 656 observations made on 242 days, 

 in nine different years, extending equally before and 

 after the 2l7th of April, from which the mean tem- 

 perature of the year in latitude 76° 45', near the 

 meridian of London, appears to be 18°.86. Before 

 proceeding to the investigation of the temperature of 

 the winter months, it will be convenient to reduce all 

 the monthly temperatures derived from my observa- 

 tions to one parallel, say, to the latitude of 78° N. 

 The observations of May, June and July, being ge- 

 nerally made near the ice, and consequently pretty 

 uniformly affected by its influence, are reduced to 

 one parallel, by applying, as a correction, the differ- 

 ence in the temperature of the mean latitude observed 

 and that of 78°, as determined by Mayers formula, 

 which, in these three instances, does not, in any one 

 case, amount to the third of a degree ; but the cor- 

 rection of the mean temperature of the year as well 

 as that of April, is, I acknowledge, more arbitrary. 

 The mean latitude of the observations for April 

 is 75° 59' or 2° V from the parallel preferred. Con- 

 sidering the circumstances as similar to those above, 



than the difference between the mean of the year, and that of 

 July ; and in London, (from the mean of twenty years obser- 

 vations,) one fifty-third part less. — Append. No. II. Table* 

 E and F, 



