Category: Pre 19th Century Instruments
Estimated Date: 1720
Name: Hourglass 15 second
Description: 4.5“h x 2 3/4” octagon shaped wooden frame. Hourglass is of the 18th century type with a resin and string joint of two bulbs. The sand in the glass runs for exactly 15 seconds, evidently for the purpose ot timing the pulse. Four wooden posts support the ends, the glass is about 1 1/2” diameter at the ends tapering to meet at the wooden joint. On one of the ends there is the number 15 scraped in. The probability that this is a medical device for timeing the pulse is discussed in: Blaufox, MD, Constable AR: The Sandglass and the Pulse. Bulletin of the Scientific Instrument Society. No. 96, 18-19, 2008.