as the exclusive property of the Smithsonian Institution, and, like the papers, was to be published immediately. Hence it is that the small map which illustrates this volume is but a copy (reduced ten diameters) of my field chart, projected on the spot from my unrevised materials. It is perhaps needless for me to observe that entire accuracy was not attainable in the field, inasmuch as I had neither the leisure nor the facilities for reducing 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 confidently relied upon this source for the correct information 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 Secretary 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 Smithsonian Institution publishing the map, for some years past in its possession,--an event which I think unlikely to happen, and which will now be unnecessary, the more especially as I am at present engaged in a new reduction of my materials, and the projection of a new map, the publication of which, in sufficiently large form to give it topographical as well as geographical value, has been proposed by my distinguished and very kind friend, Dr. Augustus Petermann, Gotha, in his Geographical Journal.