Description
ITEM 6905
‘Troughton & Simms’ 5” Transit Theodolite #6905
This is an excellent example of a late Victorian ‘Transit’ theodolite, a pattern which came to supersede the ‘Wye’, although the two styles were co-existent, at least in England, from the 1840’s until the Wye more-or-less disappeared in the early 20th century. The Transit theodolite derived its name from the ability of the telescope to transit on its axis a full 360-degrees. The drawbacks which its critics initially claimed were, a higher centre of gravity making it less stable, extra weight, and extra cost. However, these factors were more than compensated for by the ability to make backsights without removing and reversing the telescope, as was required for the Wye theodolite.
Included with this item are several accessories including a burner with support platform for making night observations. The light emitted is channelled through a lens, and through the hollow trunnion axis to the centre of the telescope. Here it is reflected to illuminate the crosshairs by a small reflector which is inserted when the burner is in use, an accessory which this item also includes. Other accessories present are, the striding-level used for precise levelling of the trunnion axis, and a 90-degree eyepiece, especially useful for astronomical observations when the telescope is steeply inclined.
The 5-inch diameter circles are divided on silver to 20-minutes of arc, with verniers to 30-seconds read by Ramsden viewers (2 with lenses absent). The mahogany case is in good condition. It contains a space for the tribrach (triangular mounting plate), but which will be sold with the tripod.
In summary, this item is recommended as an excellent example with desirable accessories.
Approximate Dimensions
Instrument: 355 mm high, 270 mm long over telescope
Case: 387 x 316 x 194 mm high
Approximate Weights
Instrument and case (excluding tribrach): 12 kg
Instrument, Case, and Tripod with tribrach: 18 kg
Prices
SOLD
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