Renseignements généraux

Nº de série

S/O

Nº de partie

2

Nombre total de parties

4

Ou

S/O

Brevets

S/O

Description générale

Non-ferrous brass

Dimensions

Remarque : Cette information reflète la taille générale pour l’entreposage et ne représente pas nécessairement les véritables dimensions de l’objet.

Longueur

S/O

Largeur

S/O

Hauteur

2,9 cm

Épaisseur

S/O

Poids

S/O

Diamètre

12,6 cm

Volume

S/O

Lexique

Groupe

Astronomie

Catégorie

Équipement d'observation

Sous-catégorie

S/O

Fabricant

Ou

Troughton Simms

Pays

England

État/province

Inconnu

Ville

London

Contexte

Pays

Canada

État/province

Inconnu

Période

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.

Fonction

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.

Technique

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.

Notes sur la région

Inconnu

Détails

Marques

None apparent.

Manque

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.

Fini

Cylinder with screw thread in the centre hole. Lacquered brass and chemically treated finishes. Reverse side is black in colour.

Décoration

S/O