Images (7)

gunners calipers

Date: 1831-1841

Inventory Number: 1998-1-1420

Classification: Gunner's caliper

Subject:

calculating instrument, mechanics,

Maker: Benjamin Pike and Son (1831 - 1841)

Cultural Region:

United States,

Place of Origin:

New York,

Dimensions:

0.4 × 17.8 × 5.3 cm (3/16 × 7 × 2 1/16 in.)

Material:

leather, brass,

Accessories: leather snap pouch

Description:

When folded, the gunner's calipers are stored in a rectangular leather pouch case that opens with a fold over button closure. The calipers are constituted of two brass arms attached by a round pivot elbow. The outer edge of both arms is straight. The inner edge of both arms begins straight at the pivot end but turns into a concave curve, finishing with a sharp inwardly directed point at the end. Both arms are engraved with various scales and charts on both sides.

Signedengraved in script on pivot elbow: Benjn Pike & Son

Inscribedengraved in script on pivot elbow: New York

engraved in script on instrument arm: Quantity of Power for / filling the Chambers of / Brass Mortars & Howitzers

engraved in script on instrument arm: Brass Guns / Proof / Service

engraved in script on instrument arm: Iron Guns / Proof / Service

engraved in script on instrument pivot elbow: the weight of iron shot

FunctionGunner's calipers were used to measure the external diameter of cannon balls, the internal diameter of cannon ball bores, to determine appropriate powder weights, and the powder rating of various guns. The concave curves and points on the inner edges of the calipers were closed around the instruments in question and gunners could read the appropriate values from the caliper arms.

For more information on the history of gunnery, more examples of and information about calipers, click here.