rs during the great rebellion. Generals Kearney, J.E.
Johnston, Pope, Warren, Fremont and Parke, and Colonels Long, Bache,
Emory, Whipple, Woodruff and Simpson, Captains Warner, Stansbury,
Gunnison and many other officers, generally in their younger days,
contributed their quota to the geographical knowledge of the country,
and made possible the wonderful network of railways guarded by
military posts that has followed their footsteps. Their reports fill
twelve large quarto volumes.

BOUNDARY AND LAKE SURVEYS.

The astronomical location of the boundaries of the several States and
Territories, as well as of the United States, is a duty frequently
required of the engineer officer, and such a survey between this
country and Mexico is now in progress. The entire line of the 49th
parallel of latitude from the Lake of the Woods to the Pacific Ocean,
which forms our northern boundary, was located a few years ago by a
joint commission of English and United States engineers, and monuments
were established at short intervals over its entire length.

A careful geodetic and hydrographic survey of the Great Northern
Lakes, including every harbor upon them and the rivers connecting
them, was carried on for many years and was finally completed some ten
years ago. Maps and charts of these surveys are published from time to
time for use of pilots navigating these waters.

Not only are the duties of the military engineer similar in many
respects to those of the civil engineer, but there are many instances
in which the duties of one branch of the profession have been
performed by members of the other branch, quite as efficiently as
though they had been performed by engineers specially educated for the
purpose. During the late civil war there were many illustrations of
this, all showing that an ingenious engineer can readily adapt himself
to circumstances entirely different from those to which he has been
accustomed. A very good example of this occurred in the Red River
expedition of General Banks and Admiral Porter. In that memorable but
disastrous campaign an army accompanied by a fleet of transports and
light draught gunboats, sometimes called "tin clads" because some
parts of them were covered with boiler plate to stop the bullets of
the enemy, ascended the Red River in Louisiana; but the advance having
been checked and a retreat commenced, it was found that the river had
fallen to such a low state that the fleet was caught above