Ship's log glass. Single sand-glass in cylindrical brass mount (end cap missing). 15 seconds. Horne Type B. ?English, second half of the 18th century

Record summary

Held and catalogued by Science Museum Group, London (object number 1991-206), this is a sand glass, made in England, dated 1750–1799. The Atlas places it in the Precision & Scientific Horology period (1750 – 1850) of its Instruments collection. The record is illustrated with 1 photograph.

Assembled from the source record's structured fields. Dates and attributions are given as the source states them; where a field is missing the Atlas leaves it blank rather than estimating.

Catalogue description

The source record does not include a narrative description. The structured fields above are reproduced from it.

Atlas type guide

Sandglasses and hourglasses

A sandglass measures an interval rather than telling the time of day: a fixed quantity of fine material runs from one bulb into the other through a narrow neck. Documented in Europe from the fourteenth century, sandglasses were used on board ship to time watches and to measure speed with the log line, in churches to time sermons, in schools, laboratories and kitchens.

Early glasses were made as two separate bulbs bound together at the neck with a diaphragm and wax and thread; one-piece blown glasses only became usual in the nineteenth century. The 'sand' could be powdered marble, eggshell or metal filings, carefully sieved and dried. Sets of graduated glasses in one frame allowed several intervals to be timed.

General guidance written by the Atlas editors about this kind of object. It is not a statement about this particular piece; for that, rely on the source record above and on physical examination.