1969 Wild Heerbrugg T2E theodolite

1969 Wild Heerbrugg T2E universal theodolite
Figure 1: 1969 Wild Heerbrugg T2E universal theodolite
This Wild Heerbrugg T2 universal instrument was part of a large donation to my collection together with a 1962 Wild T2 theodolite, a 20th c. Askania Tu400 theodolite, a 1951 Wild N2 level, a 1960s Jenoptik Koni 007 level, a 1960s Zeiss Opton Ni 2 level, a 1956 geodetic sextant, and various accessories.

Provenance
The above mentioned group of instruments once was part of the set of instruments used by the field organisation TGTW of the Survey Department (Meetkundige Dienst, 'MD' in short) of Rijkswaterstaat (part of the Dutch Ministry of Infrastructure and the Environment, responsible for the design, construction, management and maintenance of the main infrastructure facilities in the Netherlands).

The department was closed in the early 2000s and in 2008 the instruments were donated to my collection.

Development1
The Wild T2 was first produced in 1926. The archetype Wild T2 in my collection was the third modification of the first model. The instrument shown here was the fourth model T2 produced, which was produced between 1958 and 1970, and dates from 1969. It was the successor of the seven years earlier Wild T2 and predecessor of the Wild T2 mod in my collection.

Accuracy2
This Wild T2 universal instrument is equipped with glass circles (90mm diameter horizontal and 70mm diameter vertical) and a optical reading mechanism. The T2 does not have a compensator for the vertical index, a coincidence vial is used instead (see figure 6). With 70mm diameter the vertical circle of this third model T2 is substantially larger than that of the archetype model T2, while the horizontal circle remained the same.

This T2 has centesimal circles divided down to 20c (0.20gon) intervals, can be read using a micrometer directly to 2cc and estimated to at least 1cc (see figure 11 and figure 12). 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 7 and figure 8).

The T2E from the other side
Figure 2: The T2E from the other side
Alternatively the circles can be illuminated by electric lights, but sadly enough the instrument came without them.

Production
The first T2's were produced in 1926. Up to 1970 a total of 38,800 were made and many more thereafter.3 Here in the Netherlands the T2 has been the most popular instrument among surveyors for many decades and probably every surveyor educated here in the second half of the 20th century has worked with it.

According to the Ahrend Prijscourant 22 of 1962 a "T2 in metalen stolp, met optisch lood ... elektrische verlichting zonder statief, 400g..." ("T2 in metal cover, with optical plumb ... electrical lighting without tripod, 400g") would have cost fl.3,630.-.4

The instrument
This Wild T2 came complete with its steel container, lens cap and tools (see figure 9). It is centesimally divided. The telescope has a magnification power of 30 times. The inverted field of view shows four stadia hairs with a multiplication factor of 100 (see figure 10).

Centring can be done using an optical plummet, which has a normal cross-hairs for the purpose (see figure 10).

Externally there are only two differences with the 1962 Wild T2; the peep sight on the telescope has gone (see figure 5) and the locking mechanism of the tribrach is now turning instead of sliding (see figure 3 and figure 4).

Internally the presentation of the coincidence reading method of the circles has much improved and the interval of the micrometer has doubled (see figure 11 and figure 12).

Notes

[1]: See the theodolite overview page at the Virtual Archive of Wild Heerbrugg.
[2]: Wild, Universal-Theodolit Wild T2 mit automatischem Höhenindex: Gebrauchsanweisung, (Heerbrugg, 1978), p.11.
[3]: See the Products: Quantity at the Virtual Archive of Wild Heerbrugg.
[4]: Ahrend, Prijskoerant 22 Meten, (1962), pp.20-21.

If you have any questions and/or remarks please let me know.

The Wild T2E with container and accessories
Figure 3: The Wild T2E with container and accessories
 
This Wild theodolite features the final type of tribrach attachment method
Figure 4: This Wild theodolite features the final type of tribrach attachment method

Coarse aming is done using two beads.
Figure 5: Coarse aming is done using two beads.
 
The vial for the vertical circle.
Figure 6: The vial for the vertical circle.

The vertical circle is illuminated with a rotatable mirror.
Figure 7: The vertical circle is illuminated with a rotatable mirror.
 
The horizontal circle is illuminated with a rotatable circle.
Figure 8: The horizontal circle is illuminated with a rotatable circle.

The original screwdriver with adjustment tools in the handle.
Figure 9: The original screwdriver with adjustment tools in the handle.
 
The telescope has an erected view and four stadia hairs.
Figure 10: The telescope has an erected view and four stadia hairs.

The upper block shows two diametrically opposite parts of the gon divided circle.
Figure 11: The upper block shows two diametrically opposite parts of the gon divided circle.
 
At left the vertical circle reads 110.4773gon, the horizontal circle reads 89.3768gon.
Figure 12: At left the vertical circle reads 110.4773gon, the horizontal circle reads 89.3768gon.

A Roelofs Prism mounted on the Wild T2.
Figure 13: A Roelofs Prism mounted on the Wild T2.
 
The front end of the Roelofs Prism can be opened for normal use of the instrument.
Figure 14: The front end of the Roelofs Prism can be opened for normal use of the instrument.

The internal lay-out of the Roelofs Prism.
Figure 15: The internal lay-out of the Roelofs Prism.
 
This what you see through a Roelofs prism.
Figure 16: This what you see through a Roelofs prism.

Surveyor's crosses Geodetic Sextants Theodolites Total Stations Levels Standards Tools Firms
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