WASHINGTON, _April 20, 1848_.

SIR: In presenting to you the joint report of the commissioners
appointed under the treaty of Washington of August 9, 1842, to survey
and mark the line of boundary between the United States and the British
Provinces, which I have the honor herewith most respectfully to submit,
I have to perform the painful duty of informing you that the maps of
that line and of the adjacent country, which had been elaborately
constructed by the scientific corps on the part of the United States,
and contained upon 100 sheets of drawing paper of the largest size,
together with the tables of the survey, have been destroyed by the
conflagration of the building in which they were contained. This house
had been occupied by Major James D. Graham, the head of the scientific
corps and principal astronomer of the American commission, as his office
until his departure for Mexico. All the maps, drawings, and tables had
been completed and duly authenticated by the joint commissioners, and
were ready to be deposited with their joint report under their hands and
seals in the archives of this Government. Of this I had the honor to
inform you in my letter of the 24th ultimo.

I can hardly express the pain which this unfortunate event has
occasioned me. But I can not perceive that any imputation of blame can
properly be attached to any officer of the commission. The care and
custody of all the work of the United States scientific corps were
properly placed in charge of Major Graham, as the head of that corps,
who had had the immediate direction and superintendence of it from the
first organization of the commission. He required the maps and tables
at his office for reference and revision in the progress of the
astronomical work. Upon his departure for Mexico he placed Lieutenant
A.W. Whipple in his rooms with an injunction to guard with the utmost