1821, to April 30, 1822, he was assistant professor at the Military
Academy, a position for which his attainments in descriptive geometry and
his skill in drawing especially fitted him. This employment, however, was
not altogether to his taste. He was too much of an artist to wish to
confine himself to the mechanical methods needed in the training of
engineering students. In 1822, although belonging to the artillery, he was
detailed on topographical duty under Major (afterward Colonel) Abert, and
was connected with the commission employed in tracing the international
boundary between Lake Superior and the Lake of the Woods. This work
continued four years, from 1822 to 1826, and subsequent duties in the
cabinet of the commission employed nearly two years more.

The field service of this engagement was anything but light work, much of
it being performed in the depth of winter with a temperature fifty degrees
below zero. The principal food of the party was tallow and some other
substance, which was warmed over a fire on stopping at night. The snow was
then removed to a sufficient depth for a bed, and the party wrapped one
another up in their buffalo robes, until the last man's turn came, when he
had to wrap himself up the best he could. In the morning, after warming
their food and eating, the remainder was allowed to harden in the pan,
after which it was carried on the backs of men to the next stopping place.
The work was all done upon snow-shoes, and occasionally a man became so
blinded by the glare of the sun upon the snow that he had to be led by a
rope.

Upon the 1st of June, 1821, Whistler was made second lieutenant in the
First Artillery, in the reorganized army; on the 16th of August, 1821, he
was transferred to the Second Artillery, and on the 16th of August, 1829,
he was made first lieutenant. Although belonging to the artillery, he was
assigned to topographical duty almost continually until December 31, 1833,