"Preference is given to those who have acquired the most knowledge of the trade they wish to follow. No man, however, who through successive years remains persistent in his desire to show what he can do at any particular trade, is in the end denied an opportunity. Meanwhile, if a man cannot at first win entrance into the business he prefers, he has usually one or more alternative preferences, pursuits for which he has some degree of aptitude, although not the highest. Every one, indeed, is expected to study his aptitudes so as to have not only a first choice as to occupation, but a second or third, so that if, either at the outset of his career or subsequently, owing to the progress of invention or changes in demand, he is unable to follow his first vocation, he can still find reasonably congenial employment.

This principle of secondary choices as to occupation is quite important in our system. I should add, in reference to the counter-possibility of some sudden failure of volunteers in a particular trade, or some sudden necessity of an increased force, that the administration, while depending on the voluntary system for filling up the trades as a rule, holds always in reserve the power to call for special volunteers, or draft any force needed from any quarter. Generally, however, all needs of this sort can be met by details from the class of unskilled or common laborers.""How is this class of common laborers recruited?" I asked.

"Surely nobody voluntarily enters that."