Unlike the first-class clerks, the clerks of the second division are drawn mainly from the middle and lower middle classes, and their education has been obtained in the grammar schools and other schools of a similar kind. Although a distinct corps, recruited by a different examination, and intended for a lower grade of work, they are not altogether cut off from the higher positions. After eight years of service they can, in exceptional cases, be promoted to first-class clerkships, and this is sometimes done. But as the number of second division clerks appointed each year is about three hundred, and the number promoted to first-class clerkships is on the average only about four, the chance of reaching that grade is very small.[167:1] [Sidenote: Assistant Clerks.] Within the last few years a new grade, called assistant clerks (abstractor class), has been formed, recruited at present by competitive examinations among the boy clerks. The work is chiefly in the nature of copying, but an assistant clerk may for special merit be appointed to the second division without competing in the examination.[167:2] [Sidenote: Boy Clerks.] The lowest grade of officials recruited in common for a number of departments is that of boy clerks.[167:3] These come from much the same class in the community as the clerks of the second division, and the competitive examination, though more elementary, is of the same character,[167:4] the limits of age being fifteen and seventeen years. The employment is essentially temporary, and in fact boy clerks are not retained after they are twenty; but the position is a step towards further advancement, for the boy clerks alone can compete for the assistant clerkships, and if they go into the examination for the second division a credit for the service they have done is added to the marks they obtain. Yet the examination for boy clerks is one of the few competitions for a large number of positions, where the quantity of candidates is insufficient. [Sidenote: Other Competitive Examinations.]