Twelve inch portable astronomical quadrant, 1760-1769.

Richardson, Claire

 
Twelve inch portable astronomical quadrant, 1760-1769.
4 0 c m
 
34cm
actual image size: 26cm x 32cm

Description

This portable astronomical quadrant was made in London by the famous English instrument maker John Bird (1709-1776). It was sent with one of the expeditions dispatched by the Royal Society to measure the 1769 transit of Venus. Captain Cook (1728-1779), who observed the event from Tahiti on his first voyage to the South Pacific (1778-81), may have even used this particular instrument. An astronomical quadrant was employed to measure the angle of a celestial object from the zenith. Objects were sighted using a pivoting telescope fitted with cros-hair wire that moved along a radial scale graduated in degrees. The instrument's orientation in both the horizontal and vertical could be finely adjusted using the plumb bob and spirit level.

Image Details

Artist
 
Image Ref.
 
10324394

© Science Museum / Science & Society Picture Library

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