426 
APPENDIX NO. XIII. 
No. XIII. 
Contribution to our knowledge of the Climate of the American Po¬ 
lar Regions , with an accompanying illustration , by Charles A. 
Schott, Esq., United States Coast Survey . 
The relations of temperature, forming one of the most interesting 
features in the meteorology of Arctic America, demands equally, in 
preference to other studies, the attention of the navigator and phy¬ 
sicist. Following the admirable thermal investigations of Dove, and 
making use of the peculiar advantages of a graphical representation, I 
have attempted, in the accompanying chart of mean monthly isothermal 
lines, to illustrate the changes of the atmospheric temperatures from 
month to month and season to season. 
The several expeditions sent in search of Sir John Franklin have 
brought home a rich store of thermal material, but by far the greater 
part of which has not yet been made public; hence, the present map 
cannot pretend to give an elaborate and true picture of the observa¬ 
tions on file, but should be received merely as an attempt to illustrate 
the temperature-relations or part of the climatology of the American 
Arctic archipelago. In its general outlines and conclusions no great 
change is anticipated from the addition of new facts. 
In tracing the isothermal, or lines of equal average monthly tem¬ 
perature of the air, duo allowance is to be made for the short period 
over which the observations extend at most of the places,—a circum¬ 
stance of primary importance, not to be overlooked, since it is well 
known to what considerable changes the mean annual temperature 
at any given place is subject. Rink, in his valuable geographical 
description of North Greenland, gives several striking examples of 
this kind. 
The isotherms are principally based upon observations made at the 
following places:—For the northern and western part of the map, 
Melville Island, Assistance Ray, Port Bowen, Boothia Felix, Igloolik, 
and Winterinsel; for the western coast of Greenland, Jacobshavn, 
Omeack, Upernavik, Wostenholm, and the northernmost station, 
Rensselaer Harbor. Some of the results are imperfect, on account of 
too limited a number of daily observations. Dove’s curves, to which 
the necessary alterations and additions have been made, were used as a 
basis. The curves themselves were constructed by a graphical pro* 
