Herrmann Diedrich Geestmünde Chronometer Age Determination
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Who was Hermann Diedrich (Geestemünde)?
- Location: Geestemünde (today a district of Bremerhaven, then independent).
- Active: ca. 1890 – 1940 .
- Job title: Master watchmaker / Chronometer maker .
- He owned a watchmaking shop and repair workshop , possibly selling high-end imported watches.
Like other watchmakers in northern Germany (Koopmann – Bremen, Lidecke – Geestemünde, Thie – Kiel), Hermann Dietrich did not work as a manufactory , but as a master craftsman :
He sourced high-quality Swiss blanks ( Ébauches ) from A. Schild, FHF, Rebberg (Aegler), etc.
He assembled and regulated them, signing them with his name: “Herm. Dietrich – Geestemünde”, or “H. Dietrich – Geestemünde”
Types of watches
| Period | Typical watches |
|---|---|
| 1890 – 1910 | Pocket watches with enamel dials, cases made of 800/900 silver |
| 1910 – 1925 | Precision pocket watches, usually with 15 or 17 jewels, often "Rebberg" movements from Biel |
| 1925 – 1935 | Wristwatches with A. Schild or FHF movements, nickel cases, some with luminous numerals. |
| 1935 – 1940 | Late military/observer watches with German or Swiss movements (e.g. Unitas) |
Serial numbers and approximate time assignment
Since Hermann Dietrich did not have his own production facilities, the serial numbers of the watches come from the respective Swiss movement manufacturers; therefore, the age can be roughly determined based on the serial number and caliber type:
| Serial number (approx.) | Movement manufacturer / Caliber | Estimated year |
|---|---|---|
| 150,000 – 300,000 | Aegler (vineyard type) | 1900 – 1910 |
| 300,000 – 500,000 | Aegler / A. Schild | 1910 – 1920 |
| 500,000 – 800,000 | A. Schild AS 970, FHF 29 | 1920 – 1930 |
| 800,000 – 1,000,000 | A. Schild AS 1130 / Unitas | 1930 – 1940 |
Identifying features for time determination
| feature | Chronological context |
|---|---|
| Enamel dial with Roman numerals | before 1915 |
| Arabic numerals, guilloché dial | ca. 1915–1925 |
| Printed metal dial, luminous material | after 1925 |
| Silver jewelry case made of 800/900 silver with crescent moon and crown | before 1930 |
| Gold-plated or nickel cases | ca. 1920–1940 |
| Engraving “15 Rubis – Swiss Made” | 1910–1930 typical |
German chronometer and watchmaker
Hermann Diedrich was the son of Karl Johannes Diedrich . Karl Johannes was born around 1864 and completed an apprenticeship at the DUS (Deutsches Technische Schule). Chronometer testing began in 1888. Karl Johannes resided in Geestemünde (Bremerhaven), at Borriesstraße 24.
Hermann Diedrich was born around 1885 and, like his father, became a chronometer manufacturer, which he also submitted to chronometer tests; for example, four of his instruments are listed in the 18th test of the German Naval Observatory in Hamburg for the winter of 1894/95, which passed successfully alongside such famous names as Bröcking and Adolph Kittel .
Source: Wikipedia, KI, Konrad Knirim
