Compass needle

In their ongoing search for a useful auxiliary pointer for their watches, Excelsior Park rediscovered something already featured on the Second Crown called the "North Pointer," a 24-hour hand that, although not intended to show time, could be used as a direction finder outdoors.

In the chronograph watch in Figure Z31, O is the usual crown for manual setting, G´ is the crown for setting the small second hand F´, and the arrow E with the letter N is the north indicator. This watch was designed so that the hour hand pointed to the sun, and the needle pointed north. The method of determining direction using a watch is not new. Even without a compass needle, you can know that the opposite direction is north by pointing the hour hand to the sun and dividing the angle between the hour hand and the dial at 12 o'clock in half, as the line that forms points south. The needle or north pointer automatically performs the task of halving this angle. One important thing is to make sure that the north pointer is over the number 6 at 12 noon.

The pointer itself was not the first invention of Excelsior Park: in 1891 Philipp Reinhard of Bern patented a "compass hand" for pocket watches, which served the same purpose as above. Figure Z32 is taken from the patent document, but the sun has been added by the author.

Wristwatch Compass

On cloudy days, the above method of checking the direction is not possible because the north pointer cannot be aligned with the sun. In such cases, a real compass is needed. Since pocket watches often had small compasses (which often did not work very well), this method was also adopted for wristwatches. Charles Albert Nicolet, a company in Tramelan near Bern, Switzerland, patented a wristwatch compass in 1937. Since the compass was placed on the dial (see fig1 and fig2), all steel parts had to be non-magnetic to prevent the compass needle from being affected by magnetic forces.

The same was true for the hour and minute hands, which passed over the compass. Figure 2 shows a cross-section that makes it easier to see how the compass was implemented. The watch had to be held perfectly horizontal to prevent the compass needle (8) from rubbing against the dial 1 that covered it. The compass needle rested on knob 9, and was very short so it never moved out of position, but it could move out of its correct position when the watch was level. To keep it from tilting, there was a frame-like structure underneath the compass needle that fit over knob 12, and a round hole (7) in dial 1 through which the compass needle could be seen.

Calendar View

Full Calendar

Apart from the normal time display, the calendar display is probably the most useful feature of a watch. Any type of watch can have a calendar display. Chronograph watches also come equipped with various types of calendars. The simplest ones only had a hand or window showing the date, but later they were made to show the day of the week as well. Full calendar chronographs show the date, day of the week and month. The display of these on the dial varies. In older models, the date was displayed on the outermost scale of the dial and was indicated by a hand from the center. The day of the week and month were displayed in two small windows.

Figure Z34 is a typical example. On the dial, the hand G indicates the date, the window H indicates the day of the week, and the window J indicates the month. Such watches have small buttons (L and K) at various positions on the case for adjusting the calendar display.

Moon Phase

The full calendar alone did not meet all the needs. For added practicality, a moon phase was added based on the lunar display. Technically it was simple and accurate enough. Generally, the moon phase was based on a 29.5-day cycle, which required two moons and 59 graduations on the disk. The difference between the actual lunar revolution of 29 days, 12 hours, 44 minutes and 2.9 seconds and the moon phase display on a wristwatch was negligible. The moon phase disk was usually displayed as a cutout on the 12-hour subdial. The M in Fig. Z35 symbolically and practically indicates the beginning and end of the lunar cycle. The disk is usually accompanied by a dedicated adjustment button (K).

The calendar and moon phase functions are independent of the chronograph mechanism, and the combination of full calendar and moon phase can be found in other watches, such as the split-second chronograph shown in Figure Z36, where A, B, and O on the right side operate the chronograph, and buttons L and K adjust the calendar and moon phase. Depending on the type of case, buttons L and K may or may not be visible.

Perpetual calendar

The highest technical level was reached by the chronograph with perpetual calendar, which is produced to this day by several well-known Swiss watch companies. Leading them all is Patek Philippe in Geneva. This company patented the perpetual calendar for pocket watches on May 23, 1889, and later developed the mechanism for wristwatches. Perpetual calendars can be equipped on both regular and chronograph wristwatches, and have the function of automatically distinguishing between months with 31 and 30 days, as well as the leap year month of February. If the leap year is not displayed, it is impossible to know whether the watch has a perpetual calendar or not. The so-called "four-year wheel" is essential for the perpetual calendar, which switches between four lunar (48-month) cycles by means of steps of gears of different heights. These steps are driven by a lever that activates the precise date display in sequence. In recent years, these perpetual calendar functions have been newly developed by several companies. IWC has developed a mechanism that allows the mechanism to be set quickly without the need for correction. The moon phase is controlled, so no correction is required.