The Split Centre Seconds is not quite so complicated as the last named. It has two centre second hands revolving round the dial, the one directly over the other, as also, in another part of the dial, a small hand revolving five times in a second. Upon pressing a stop-piece one of the long second hands is stopped, and another pressure will stop the other—the space between the two hands will then indicate precisely the time occupied by the event which it is desired to measure. Another push to the stop-piece will make both hands again fly together, and enable the operator it may be to make a new experiment or observation.
The Perpetual Calendar Keyless Watch, shows on its dial the year, the month of the year, the day of the month, the day of the week, the phases of the moon, as well as hours, minutes, and seconds. It requires no setting, as the old-fashioned Calendar Watch did at certain intervals, but, by a very ingenious contrivance, the changes from month to month, as for example from February 28th to the 1st of March, or from 30th or 31st of other months to the 1st of the next, are all performed by the watch, which also of itself marks the extra day for Leap Year. When to all the above are added, as is sometimes done, the Minute Repeating Work to repeat the hours, quarters, and minutes, it may be said that the power of complication can no farther go within the limits of
The Perpetual Calendar Keyless Watch.
the small box which is called a watch case,—for these watches are provided with either Lever, Duplex, or Chronometer Escapements as may be preferred, and with compensation balances adjusted to serve in extremes of temperature. But in the examples set forth in the following illustrations, it will be seen that superadded to all the foregoing are a thermometer, and an index showing the calendar by the old and new style, as indicated by the words Gregorian and Russian,—the former referring to Pope Gregory who decreed the alteration to the new style, and the latter to the fact that the Russians still reckon by the old style.
The Complicated Perpetual Calendar and Independent Seconds Keyless Watch, is another example of this kind of mechanism, which, without being re-set from time to time for leap year and other changes, keeps a perpetual register of seconds, minutes, hours, days, weeks, months, and years, shows Old and New Styles, the phases of the moon, and variations of heat and cold. It has also two separate trains of wheels and two mainsprings, both of which are wound up by the button at the pendant. It will be seen that the dial has two hour circles with hour and minute hands showing separate time. Below the centre is the sunk seconds dial with two seconds hands, the one over the other, and each working independently, so that the one may be stopped by a push at the button of the pendant and yet the other go on, to be in its turn stopped, so that the operator may use it as a stopwatch. Underneath the hour hands of each circle is the hand showing the month and the day of the week. The two centre hands, with the letters G and R, are pointing to the days of the month, and showing the Gregorian and Russian day. In the small square space just below the centre is the year, and below this and lying over the second hands is another hand pointing to the degrees of temperature to which the watch is exposed; near the top of the dial is a small plate showing the phases of the moon,—the position indicated in this illustration is that of full moon.
The Meridian Watch shows the time of day in any number of places in any part of the world. It is set to Greenwich time, and marks the difference between this and the time of all the great metropolitan cities in both hemispheres,—as St Petersburg, Constantinople, New York.