1990 Wild Heerbrugg T2 mod with DI1000 DISTOMATThis Wild T2 theodolite, also known as the Wild T2 mod, arrived in the collection in September 2015. It was formerly owned by the Maritime Institute Willem Barentsz (MIWB) on Terschelling, where it has been used from 2002 until 2014 for teaching purposes, mainly for traversing and sun azimuth observations using a Roelofs prism (see figure 25 and figure 26). At the start of the new academic year 2015-2016 it was replaced by a more modern Leica TCRA1101 from 2001, which also is used for the same observations.
The Wild T2 mod was the last version of the T2, a theodolite that started in 1926 with the archetype Wild T2. Compared to the previous model T2 the T2 mod had several new features:
The T2 mod was not the first Wild theodolite with a compensator for the vertical circle. In the end of the 1950s the Wild T1A was the first to show this feature. The main difference with the compensator featured on the T2 mod is that the latter is a mechanical one, whereas the one on the T1A works with a liquid.
This Wild T2 universal instrument is equipped with glass circles (90mm diameter horizontal and 70mm diameter vertical) and a optical reading mechanism. The T2 mod has a compensator for the vertical index (see figure 11). With 70mm diameter the vertical circle of this final model T2 is substantially larger than that of the archetype model T2, while the horizontal circle remained the same.
This T2 mod has centesimal circles divided down to 20c (0.20gon) intervals, can be read using a micrometer directly to 1cc (0.1mgon) and estimated to 0.1cc (0.01mgon, see figure 23), although that is beyond the T2's accuracy. The circles are illuminated by two distinctive rotating mirrors: one directly on the secondary axis and one at the base of the instrument (see figure 17 and figure 18).
The accuracy of the compensator for the vertical circle increased from 1" at the T1A to 0.3" in the T2 mod.1
The T2 mod could be equipped with various types of EDM (Electronic Distance Measurer). For this the lower optical bead has to be removed and replaced by a dedicated mounting bracket (see figure 24, figure 7, and figure 8).3 This particular instrument came with a Wild Heerbrugg Di1000 distomat. It too originates from around 1990 and still is in working order (see figure 10). In contrast to the DI3S the Di1000 consists of a single unit (the DI3S has a separate controller). Its accuracy is stated as 5mm+5ppm for normal measurements and 10mm+5ppm in tracking mode.2 Taking a measurement in normal mode takes 5 seconds. In tracking mode the first measurement takes 3 seconds and each following one 0.3 seconds.
The Di1000 EDM came in its own case, together with the original battery, charger, cables, raincoat and manual (see figure 5). The Di1000, power cable and battery also fit in the case of the T2 mod (see figure 6).
Notes: Wild Heerbrugg, Wild T2, Universal Theodolite with automatic index, Instructions for Use, (Heerbrugg, 1981), p.10.
: Wild Heerbrugg, Distomat Wild Di1000: Gebrauchsanweisung, (Heerbrugg, 1987), p.51.
: Please note that the bracket shown here is for the older types of Wild EDM and lacks the small depression for the electrical connector of the Di1000. In order to avoid short circuiting the Di1000 a piece of electrical isolation tape should be pasted on the surface of the bracket.
If you have any questions and/or remarks please let me know.
19th C. SDL 1919 K&E 1926 Zeiss RThII 1924 Zeiss Th1 1929 Wild T2 1937 Wild T3 (astronomic) 1939 Wild T3 (geodetic) 1943 CT&S Tavistock 1948 Wild T1 1952 Wild RDH 1956 Wild T0 1961 Wild T1A 1961 Wild MIL-ABLE T2 1962 Wild T2 1963/76 Wild T2 - DI3S 1963 Wild RDS 1966 Kern DKM2 1969 Wild T2E 1976/79 Wild T2 mod - DI4 1990 Wild T2 mod - Di1000 20th c. Askania Tu400