n the staff departments, and large numbers of persons from civil life
have been appointed into the volunteer staff in the Adjutant-General's,
Judge-Advocate's, Quartermaster's, Commissary, Medical, and Pay
Departments. The ordnance duties are performed by officers detailed from
the line, and engineer duties by regiments assigned for that purpose. A
large number of additional aides-de-camp were also authorized, forming
that branch of duty into a department. Aides-de-camp are also detailed
from the line. The highest rank yet created for volunteer staff officers
is that of colonel in the aides-de-camp. The heads of staff departments
at corps headquarters are lieutenant-colonels, including an assistant
adjutant-general, assistant inspector-general, a chief quartermaster,
and chief commissary. Many regular officers hold these volunteer staff
appointments, gaining in this manner additional rank during the
war--still retaining their positions in the regular service; in the same
manner as many regular officers are field officers in volunteer
regiments.

The aggregate _militia_ force of the United States (including seceded
portions), according to the last returns, was 3,214,769. The reports of
the last census increase this to about 5,600,000, which exceeds to some
extent the number actually _fit_ to bear arms. The computed proportion
in Europe of the number of men who can be called into the field is about
one-fifth or one-sixth of the population. If the population of the
entire United States be assumed to be 23,000,000, the number of men
liable, according to this computation, would be about 4,000,000, which
is sufficiently approximate. The European computation of the force to be
kept as a _standing army_ is a hundredth part of the population--varied
somewhat by circumstances. This would give the United States a force of
230,000. It will be seen how greatly inferior our regular force has
been and still is to the computations adopted in Europe. But the United
States will probably never require such a large force to be permanently
organized; for we have not, like the European powers, frontiers to
protect against nations with whom we may at any time be at war, nor
oppressed nationalities to retain in subjugation by force. Our frontiers
on Canada and Mexico have good natural defences--the first by the St.
Lawrence river and lakes, and the second by the great distance to be
traversed by an invading army before it could reach any import