The term "semimicrograph" is a portmanteau of the Latin semi (half), the Greek mikro (small), and the Greek graph (writing). It refers to a stopwatch with a scale division of 0.02 (1/50) seconds.

To measure fiftieths of a second, the clock's balance must perform 50 semi-oscillations per second. This corresponds to a frequency of 25 hertz, which is 10 times faster than a normal pocket watch balance, which oscillates at 2.5 hertz. The balance's movements are therefore no longer perceptible to the human eye.

The oscillations of a micrograph are twice as fast, at 50 Hz = 100 semi-oscillations per second. Theoretically, this can measure 1/100 of a second. However, human reaction speed must be taken into account, which is in the tenths of a second range. This means that the high accuracy of these stopwatches cannot be utilized when operated manually. Therefore, most stopwatches operate with a tenth-of-a-second division.

The movement design of a semi-micrograph is similar to that of a column-wheel chronograph. To prevent the movement from running down prematurely, the balance is started with a small starting lever at 4 o'clock. In the movement shown here, this lever engages the circumference of the lever disc.

Semi-micrographs are often equipped with a split second hand that allows for timing of intermediate times. In the adjacent image, the second hand (blue) has already completed three rotations of the dial (3 x 6 seconds) and is at one second and 18/50. The split second hand (gold-colored) has stopped at 26/50.

Stopwatches of this type were kept in a metal case to protect them on the way to the sports field or into the field. Before use, the holder must be opened and the watch removed.

Description:

Interesting Heuer short-time stopwatch with ratrappante function, FL Löbner, so-called Semikrograph, ca. 1915

Case diameter: 58mm, approx. 127g, blued iron case, numbered 83542 inside, numbered and marked 2/F68 outside

Anchor movement of finest quality, presumably manufactured by Heuer, as the Semikrograph was patented by Heuer, very beautifully preserved enamel dial, marked FL Löbner Berlin W, Semikrograph, Swiss patent number 73392/93, functional

The black gunmetal casing also speaks for military use

These short-time stopwatches were primarily used for military short-time measurements and were also supplied to the German military, among others. The rare semi-micrograph completes a full rotation in just 6 seconds, allowing the measurement of tenths and fiftieths of a second (important for artillery!). The rattrapante function allows for the measurement of intermediate times.