XIII. 



N. America. — Lake Athabasca. Lat. 59° N. Long. 111° W. Greenw. 



Corrections to be applied to the Means of the Hours of Observation to obtain the true 

 Mean Temperatures of the respective Days, Months, and of the Year. — Lefroy. 



The corrections for April and May are derived from observations made at Fort Simpson, Lat. 62° N. 

 Degrees of Fahrenheit. 



E 



The numbers without sign must be added ; those with the sign — must be subtracted. 



25 



