GEODETIC FIELD CLOCKS
Geodetic field clocks were used by measuring the arc of a pendulum swing in relation to the gravitational pull of the earth and its geographical positioning, which in turn enabled a scientist to establish the exact distance to the centre of the earth, or an unknown height. This process was known as Schwerebestimmung or Gravity Fixing. In 1896 Strasser & Rohde received orders to make Geodetic Field clocks for the Royal Prussian Geodetic Institute in Potsdam, the Central European Bureau for Latitudinal Measuring, the German Navy, The Danish Army, The Imperial Russian War Ministry and the Science Museum, London. The German South polar Expedition of 1901-1903 took a half second field clock with them on their expedition.
Earlier half-second field clocks, Nos. 141, 174, 193, 194 and 238 had identical specification but were equipped with Strasser & Rohde mercury compensated pendulums costing 450DM. Records show that in January 1914 the pendulum for field clock No. 174 was exchanged for a Riefler pendulum at the cost of 600DM. The present Strasser & Rohde No. 285 was the first half-second field clock to be delivered with its original Riefler pendulum. The pendulum was delivered to Strasser & Rohde on 21 October, 1904, then in 1905 the clock was sent to its new owner, thought to be the the Imperial Russian War Ministry.