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Bubble Units for Mk IX Sextant


This is a set of three bubble attachments for sextants in an unvarnished wooden shipping box. Each instrument is black, metal and consists of three lenses, two of which face each other and a third, between them, set at a diagonal. The first lens is crossed by very fine lines and contains a bubble. The three sextants are held in place in the box by small screws.

Accession Number: 2017.ast.44 (DAA-0129)

Alternative Name: Bubble, Bubbles

Primary Materials:

Iron Alloy, Glass, Wood, Hexane Paraffin (in bubble chamber)


Stamped on the top of the box: “A M”

On the exterior of the box, on a sticker, handwritten: “3 spare bubbles for Mark IX or Mark IXA Sextants Oct 21/69”

Dimensions (cm): Box: 22cm x 15.7x 7.4cm


These bubble units can be affixed to the Mark IX Bubble Sextant made by Henry Hughes & Son from 1938. This is a sextant intended for use in an aircraft to navigate. The bubble enables the user of the sextant to form an artificial horizon.


Good. The surface of the instruments is scratched in parts, but they appear to be intact. All three have been stored screwed into their original shipping box, but do appear to have been used.

Associated Instruments:

Manufacturer: Henry Hughes & Son

Date of Manufacture: 1938-1964


The stamp on the top of this box indicates that the bubbles were once in the ownership of the British Air Ministry.

This object was likely moved from the David Dunlap Observatory in Richmond Hill in 2008, upon the sale of the observatory. It was stored at the Department of Astronomy and Astrophysics until 2017, when it was moved to a new storage location in McLennan Physical Laboratories.

Additional Information and References:

These bubble units are associated with the Mark IX Bubble Sextant first sold by Henry Hughes & Son in 1938.

Historical Notes: