General Information

Serial #

N/A

Part Number

3

Total Parts

4

AKA

N/A

Patents

N/A

General Description

Brass

Dimensions

Note: These reflect the general size for storage and are not necessarily representative of the object's true dimensions.

Length

N/A

Width

N/A

Height

N/A

Thickness

N/A

Weight

N/A

Diameter

N/A

Volume

N/A

Lexicon

Group

Astronomy

Category

Observation equipment

Sub-Category

N/A

Manufacturer

AKA

Troughton Simms

Country

England

State/Province

Unknown

City

London

Context

Country

Canada

State/Province

Unknown

Period

This instrument presumably used 1872+

Canada

Instrument used by Topographical Survey (Div), Dept. of the Interior. It was reportedly among the instruments used on 49th parallel boundary survey of 1872-1874. It was also said to have been used in the survey of the railway belt required by the entry of BC into Confederation in 1871.

Function

Used to measure differences in zenith angles (angular distance) of stars from the zenith and thereby to determine the latitude of the instrument's location.

Technical

From Chauvenet, v. II, p. 340: The zenith telescope is a portable instrument specially adapted for the measurement of small differences of zenith distance. It is essentially the invention of Capt. Andrew Talcott, of the U. S. Corps of Engineers (in 1834); but, having been exclusively adopted in the U. S. Coast Survey for the determination of latitudes, it has there received several improvements, which have given it a more general character than it possessed at first. As now constructed [1891], it can be used at all zenith distances, and may be regarded as designed for the comparison of any two nearly equal zenith distances in any azimuths. The method of finding the latitude by this instrument, now known as Talcott's Method, is one of the most valuable improvements in practical astronomy of recent years, surpassing all previously known methods (not excepting that of bessel by prime vertical transits) both in simplicity and in accuracy.

Area Notes

Unknown

Details

Markings

N/A

Missing

Some small component parts, hardware etc. missing. Presumably would have been used with striding level over mounting arm, and possibly tube or spirit level fitted to vertical circle; Diagonal eyepiece missing.

Finish

Lacquered brass and chemically treated finishes.

Decoration

N/A