orders, and more under the control of their officers, in dangerous situations, than white soldiers.

II. Skill and appreciation of their duties, with reference to the quality of the work performed.

White soldiers are more intelligent and experienced, and, of course, more skillful, than back ones, but they have not generally a corresponding appreciation of their duties. As a consequence, I have, in most cases, found the work as well done by black as by white soldiers.

III. Industry and perseverance, with reference to the amount of work performed.

White soldiers work with more energy while they do work than black ones, but do not work as constantly. Black soldiers seldom intermit their labors, excepting by orders or permission. The result, as far as my observation extends, is, that a greater amount of work is usually accomplished with black than with white soldiers.

IV. If a certain work were to be accomplished in the least possible time, when enthusiasm and direct personal interest are necessary to the attainment of the end, would whites or blacks answer best?

Whites. Because, though requiring more effort to control, they possess a greater energy of character and susceptibility of enthusiasm than the black race, which can be called into action by an emergency or by a sufficient effort on the part of their officers.

V. What is the difference, considering the above points, between colored troops recruited from the free States and those from the slave States?

I have observed a decided difference in favor of those recruited from the free States.

The problem involved in the foregoing investigation is more difficult of a solution than appears at first sight, owing to the fact that the degree of efficiency peculiar to any company of troops depends so much upon the character of their officers, and element that must be eliminated from the question in order to ascertain the quality of the material of which the troops are composed.

I have the honor to be, your obedient servant,

H. FARRARD,

First Lieutenant New York Volunteer Engineers.

NOTE Numbers 20.

THE MAIN MAGAZINE, TELEGRAPH OFFICE, LOOKOUT, AND LATRINES IN THE SECOND PARALLEL.

These structures, built together for economy of space and material, are shown in plan and section by Figs. 23, 24, and 25 [pp. 332, 333.] The magazine frame was of heavy timbers, sheered with plank. Sand-bags were used for rivetting throughout.

NOTE Numbers 21.

SPLINTER-PROOF SHELTERS.

The splinter-proof shelters built in the approaches (chiefly in the second parallel) for the protection of the guard of the trenches and the garrisons of the batteries, are represented by sections and elevations in Figs. 26, 27, 28, 29, 30, and 31. [p. 334.]