Vlll PREFACE. 



is perhaps needless for me to observe that enth^e 

 accuracy was not attainable in the field, inasmuch 

 as I had neither the leisure nor the facilities for re- 

 ducing the magnetic variation, nor for obtaining the 

 absolute time. I am happy to say, however, that 

 no greater discrepancy exists than the one which 

 places my highest latitude two minutes too far south 

 on the field chart ; but the reductions having been 

 made, and a chart projected therefrom, I had con- 

 fidently relied upon this source for the correct infor- 

 mation which the Smithsonian Institution now alone 

 possessed. This failing me, I was obliged to fall back 

 upon my original resources, as the time was too short 

 for a new reduction. I am glad to say, however, 

 that the field chart is sufficiently accurate for every 

 practical purpose, and differs chiefly from the one 

 prepared, with greater carefulness, and of large size, 

 for the Smithsonian " Contributions to Knowledge," 

 in the unimportant feature of the names applied to 

 newly discovered places, some of which were changed 

 after my return. No list of these alterations having 

 been preserved, and being unable to get the more 

 accurate map again into my hands from the Sec- 

 retary of the scientific institution in whose care it 

 had been placed, as before observed, for publication, 

 I have simply adopted the original nomenclature, and 

 have used the names as they appear in my journal 

 and on my field chart. This explanation is made in 

 anticipation of the possible contingency of the Smith- 

 sonian Institution publishing the map, for some years 



