After striking eight bells the clock repeats, although the ship’s bell is generally struck in accordance with the two dog watches (which are of two hours’ duration each) before commencing the evening watch (8 to 12 p. m.). It will thus be seen that the clock should strike eight at 12 m., 4 p. m., 8 p. m., 12 p. m., 4 a. m., and 8 a. m.
Fig. 100. The pins on the count wheel of the ships bell clock.
In order to strike the blows in pairs two hammers are necessary, see [Fig. 98]; these hammers are placed close together, but not in the same plane. The pin wheel has twenty pins, see Figs. [98], [99], [100]; some of these pins are shorter than the others, so that they do not operate one of the hammer tails. These are shown graphically in [Fig. 100]; where the two oblong marks at figure 1 represent the tops of the hammer tails shown in [Fig. 99]. It will be seen by studying [Fig. 100] that with the wheel moving from left to right, the inside hammer tail will be operated for one blow, while the outer hammer tail will not be operated at all, thus giving but one blow, or “bell.” At the next movement of the pin wheel, the outside hammer will be operated by the long pin and the inside hammer by the short pin, thus giving one blow of each hammer, or “two bells.”
Fig. 99. Enlarged view of striking work, ships bell clock.
We now have these hammer tails advanced along the wheel so that the outside one is opposite the figure 3 in the drawing, while the other is opposite the figure 2, with one pin between them. The next movement of the pin wheel advances them so that the outside hammer will pass the next short pin and consequently that hammer will miss one blow and the pair will therefore strike three—one by the outside hammer and two by the inside. It thus goes on until the cycle is completed, eight blows being struck with the last four pins. The striking in pairs is effected by having the two hammer tails close together, so that the pins will operate both hammer tails quickly and there will then be an interval of time while the wheel brings forward the next pins. This is so spaced that the interval between pairs is three times that between the blows of a pair and the hammer tails should not be bent out of this position, or if found so they should immediately be restored to it. Tolling the bells, instead of striking them properly, is very bad form at sea and generally leads to punishment if persisted in, so that the jeweler will readily perceive that his marine customers are very particular on this point, and he should go any length to obtain the proper intervals in striking.
The pin wheel moves forward one pin for each couple of blows or parts of a couple, the odd blows being secured by the failure of the blow when the hammer tail passes the short pin. Thus it moves as far for one bell as for two bells; as far for three bells as for four, etc. The result is that the count wheel has no odd numbers on it, but instead two 2’s, two 4’s, two 6’s and two 8’s; the first two are counted on the count wheel, but only one is struck on the pin wheel, owing to the short pin; this is repeated at three, five and seven, when four, six and eight are counted on the wheel, but the last blow fails of delivery, owing to the short pin in the pin wheel at these positions.