In order to satisfy themselves as to the actual function of the spring detent escapement for marine timekeepers, in March 1804 the Board of Longitude ordered rival Thomas Earnshaw and John Roger Arnold each to make a scale model of their inventions. The cost of producing these models was to be met by the Board. Considering it is only roughly made, mostly from pieces of scrap metal, Earnshaw charged a high price of £53 10s. for his work, more than five times that charged by Arnold. Ultimately both parties were awarded £3000 for their work in advancing the technology of timekeepers for use at sea. The debate as to who did, in fact, invent the disputed escapement still continues today.

Carrying Box

Standard early 20th century plain mahogany chronometer guard box with leather carrying strap, measuring 260mm high, 280mm wide, and 233mm deep.

The box is of concealed dovetail construction. The top of the upper half has a white printed label (“Form No 426”) from the RGO, with the added typescript: “MODEL CHRONOMETER / ESCAPEMENT / Made by THOS. EARNSHAW in 1804 to the order of / The Board of Longitude. Cost £52 10s.”
The front of the upper half has the standard semi-circular projection, mating with a hollow in the front of the lower half, and having a brass hook, securing the box closed with a brass eye in the lower half. The base of the lower half has a rounded edge and projects beyond the sides of the box, a few mms to front and back but extended on the left and right, having curved ends, to form ‘tabs’ by which the box may be screwed down to the deck, each tab having a hole at its centre.

The inside of the upper half retains its green baize padding, stuffed with horsehair, and has two small brass ‘bridge pieces’ screwed on the back for retaining the winding key (missing). The lower half has had the baize padding removed and four corner blocks screwed and glued in place to support the escapement model. The eleven hole, 21mm wide leather strap is fixed to each side by three brass screws and secures with a brass buckle and two loops to form the carrying handle.