must turn through one division, which will bring the number 7 to the index; the dial B must turn through three divisions, which will 0 bring to the index; this will render a carriage necessary, but that carriage will not take place during the present motion of the dial. The dial C will remain unmoved, since 0 is at the index below it; the dial D must turn through nine divisions; and as, in doing so, the division between 9 and 0 must pass under the index, a carriage must subsequently take place upon the dial to the left; the remaining dials of the row T, fig. 1, will remain unmoved. In the row D2 the dial A2 will remain unmoved, since 0 is at the index below it; the dial B2 will be moved through five divisions, and will render a subsequent carriage on the dial to the left necessary; the dial C2 will be moved through five divisions; the dial D2 will be moved through three divisions, and the remaining dials of this row will remain unmoved. The dials of the row D4 will be moved according to the same rules; and the whole scheme will undergo a change exhibited in Fig. 2; a mark (*) being introduced on those dials to which a car-
Fig. 2.
