h more
frequently used in principle. Let E in fig. 15 be the scape-wheel
turning in a minute, and e its pinion, which is driven by the wheel D
having a pinion d driven by the wheel C, which we may suppose to turn
in an hour. The arbors of the scape-wheel and hour-wheel are distinct,
their pivots meeting in a bush fixed somewhere between the wheels. The
pivots of the wheel D are set in the frame AP, which rides on the
arbors of the hour-wheel and scape-wheel, or on another short arbor
between them. The hour-wheel also drives another wheel G, which again
drives the pinion f on the arbor which carries the two arms fA, fB;
and on the same arbor is set a fly with a ratchet, like a common
striking fly, and the numbers of the teeth are so arranged that the
fly will turn once for each turn of the scape-wheel. The ends of the
remontoire arms fA, fB are capable of alternately passing the notches
cut half through the arbor of the scape-wheel, as those notches
successively come into the proper position at the end of every
half-minute; as soon as that happens the hour-wheel raises the movable
wheel D and its frame through a small angle; but, nevertheless, that
wheel keeps pressing on the scape-wheel as if it were not moving, the
point of contact of the wheel C and the pinion d being the fulcrum or
centre of motion of the lever AdP. It will be observed that the
remontoire arms fA, fB have springs set on them to diminish the blow
on the scape-wheel arbor, as it is desirable not to have the fly so
large as to make the motion of the train, and consequently of the
hands, too slow, to be distinct.

Another kind of remontoire is on the principle of one bevelled wheel
lying between two others at right angles to it. The first of the
bevelled wheels is driven by the train, and the third is fixed to the
arbor of the scape-wheel; and the intermediate bevelled wheel, of any
size, rides on its arbor at right angles to the other two arbors which
are in the same line. The scape-wheel will evidently turn with the
same average velocity as the first bevelled wheel, though the
intermediate one may move up and down at intervals. The transverse
arbor which carries it is let off and lifted a little at half-minute
intervals, as in the remontoire just now described; and it gradually
works down as the scape-wheel turns under its pressure, until it is
freed again and lifted by the clock-t