An observatory magnifier

[Joseph Crabtree observatory magnifier].

Surveying and navigational instruments
  • Author: Anonymous
  • Publication date: late nineteenth century
  • Physical description: Brass with glass dome.
  • Dimensions: (diameter) 22cm (8.5 inches).
  • Inventory reference: 12771


Brass and glass domed observatory magnifier.

The observatory magnifier is believed to have been designed in 1804 by the legendary British inventor and polymath Joseph Crabtree (1754-1854). It was intended to aid the reading of nautical charts aboard ship, and is still in use today. The present example is particularly large measuring 22 centimetres in diameter.