Various minor changes, dictated by experience and the need for economy in manufacture, were made in these movements. After about the first thousand the diameter of the balance was reduced from approximately .700 to about .530 inch. This smaller wheel was, of course, much more suitable to vibrate at the faster speeds required on the models beating eighths and tenths of a second. At some time between the manufacture of watches bearing serial numbers 3135 and 3622, the formerly separate winding pawl and spring were combined into one piece that could be entirely made in a punch press. Another economy move was to stamp the name and patents in place of hand engraving. For a long time hand engraving was used, although stamping had been used from the beginning on the earlier rotary watch.
The case was very similar to that used on the rotary. The dial, of white enamel with snap rim fastened by a screw,[39] carried three graduated circles, an outer circle graduated in seconds up to sixty surrounding two smaller subsidiary dials. The top one of these smaller dials recorded minutes elasped up to ten and the lower one recorded fractions of a second. The same dial was used on movements indicating quarters and eighths of seconds, all being graduated in eighths. A dial without provision for indicating the fractions of a second on a separate small dial may be seen in figure 17. This last has been made into a stand for hair spring work and is shown with balance and spring just as it came from the Auburndale factory with balance spring and wheel for a timer still in place.
[Illustration: Figure 18.--TAG DISPLAYING DIRECTIONS FOR USE OF THE AUBURNDALE TIMER.
The sweep second hand and the minute register hand are attached to heart-shaped cams friction driven from their respective staffs. They are reset by a bar pivoted beneath the dial and actuated by the stem through pressure on the crown. An original instruction tag as sent from the factory with these timers is seen in figure 18.
Figure 19 shows the mechanism of the split-second model as represented in U. S. patent 220195 of September 30, 1879, issued to William A. Wales and assigned to William B. Fowle.[40] A split-second mechanism is used to time the finish of two horses in the same race or any other similar event. In usual watches of this nature the watch will run along indefinitely with the extra or split second hand stopped although this hand will not record more than a difference of one minute from the main sweep hand. This was not true of the Auburndale, as pointed out in the instructions. The reason for this is that motion is conveyed to this hand through a hair spring which would be damaged if allowed to overwind. To prevent this a stop is interposed which will halt the entire watch unless directions are followed. The serrated wheel _F_, of hardened steel, driving the second sweep hand, is cut on the edge with 120 serrations; stopping of this hand therefore is only to the nearest half second regardless of how minutely the escapement is dividing time. This is rather a serious defect as, if timing a horse race as an example, the time of the fastest horse is taken on this hand which registers a lesser degree of accuracy than the time recorded on the second and less important horse. A general view of one of these watches is seen in figure 20.