Editor’s note: Gordon A. Lange’s earlier article, “The Workings of an Early Detex Newman Watchclock,” appears in the June 2000 Bulletin and provides additional information on the function and performance of watchclocks.

 Of the watchclocks produced by Detex during recent years, the Newman is probably the best known model. It has been in production by Detex for more than 70 years. One hundred years have passed, however, since the basic model was introduced by A.A. Newman of Germany. He introduced the portable watchclock bearing his name in 1902. It was patented June 18, 1901, and received the first approval of a portable system from the then newly established Underwriter’s Laboratories (UL). (UL was established in 1901 to measure conformity with standards of the National Board of Fire Underwriters.)

The Guardsman is a much more recent model, first developed by Detex in 1940, but not introduced to the marketplace until 1946, after a delay caused by World War II.

Figure 1 shows a front view of a Guardsman with the station keyhole cover open. This rotating cover offers additional protection against dirt or moisture entering the mechanism as compared to the Newman design with its uncovered side opening.

Although a relatively recent design, the basic recording concept used in the Guardsman dates from the very first portable watchclock, the J. Bürk “drum” clock, patented in Schwenningen a/N, Germany, in 1855. This clock, according to an 1861 instruction sheet, used a “paper strip” as a recording chart and a station key that recorded the mark of the respective station on the strip. The strip was to be replaced daily.

While the Newman uses a 12 or 24-hour circular paper chart, referred to in the watchclock industry as a dial, the Guardsman uses a paper strip or tape that provides for two weeks’ recording. The used portion of the strip must be removed at least every four days or it may bind in the mechanism. More about this later in the detailed description of the configuration and operation of the recording mechanism in the Guardsman.

As Detex did with the drive hole shapes on the dials for their other watchclocks, the tape used in the original 1940 design had the Detex name incorporated into the drive holes. The tape drive sprocket had pins in the shapes of the letters

D - E - T - E - X. This name was spelled out four times around the circumference of the sprocket. The tape had its drive holes in the same shapes over and over again for the length of the tape. This was done as a defense against other companies producing the tapes.

When the watchclock was finally brought to market in 1946, this concept, because of its complexity, was dropped and the sprocket redesigned with plain drive pins and the tape with plain round holes along one border. Figure 2 shows a section of the tape used in the Guardsman. This figure is approximately one half actual size.

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