This helmet consists of a copper bonnet attached to a 12-bolt corselet which held in place a fully sealed diving suit. The position of a non-adjustable exhaust valve at the back of the bonnet and the presence of an associated exhaust bridge suggest a construction date of 1844. Heavy solder around this feature reveals the bridge to be a modification indicating an earlier date of manufacture of between 1840 and 1844 - making it the second oldest diving helmet to survive.

The side ports are of convex glass, but the screw-in faceplate is flat glass and not original. A basic spitcock (outlet tap) has also been added probably after 1870. The makers name is stamped into the front centre of the corselet, a practice which continued until the 1870s when the Siebe Gorman company began to attach name plates.

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