Hourglass in a three-legged stand

Factors affecting the amount of time that the hourglass measures include: the volume of sand, the size and angle of the bulbs, the width of the neck, and the type and quality of the sand. Alternatives to sand that have been used are powdered eggshell and powdered marble.^[1] (Sources do not agree on the best internal material.)

Hourglasses are still in use, but typically only ornamentally or when a relatively approximate measurement of time is needed, as in egg timers for cooking or board games. Hourglass collecting has become a niche but avid hobby for some, with elaborate or antique hourglasses commanding high prices.

Temperance bearing an hourglass; detail of Lorenzetti's Allegory of Good Government, 1338

History

Hourglasses are said to have been invented at Alexandria about the middle of the third century, where they were sometimes carried around just as people carry watches today.^[2] It is speculated that it was in use in the 11th century, where it would have complemented the magnetic compass as an aid to navigation. Recorded evidence of their existence is found no earlier than the 14th century, the earliest being an hourglass appearing in the 1338 fresco Allegory of Good Government by Ambrogio Lorenzetti.^[3] Written records from the same period mention the hourglass, and it appears in lists of ships stores. One of the earliest surviving records is a sales receipt of Thomas de Stetesham, clerk of the English ship La George, in 1345:

The same Thomas accounts to have paid at Lescluse, in Flanders, for twelve glass horologes (" pro xii. orlogiis vitreis "), price of each 4˝ gross', in sterling 9s. Item, For four horologes of the same sort (" de eadem secta "), bought there, price of each five gross', making in sterling 3s. 4d.^[4]

Practical uses

3-minute egg timer

From the 15th century onwards, they were being used in a wide range of applications at sea, in the church, in industry and in cookery.

During the voyage of Ferdinand Magellan around the globe, his vessels kept 18 hourglasses per ship. It was the job of a ship's page to turn the hourglasses and thus provide the times for the ship's log. Noon was the reference time for navigation, which did not depend on the glass, as the sun would be at its zenith.^[6] More than one hourglass was sometimes fixed in a frame, each with a different running time, for example 1 hour, 45 minutes, 30 minutes, and 15 minutes.

Modern practical uses

While they are no longer widely used for keeping time, some institutions do maintain them. Both houses of the Australian Parliament use three hourglasses to time certain procedures, such as divisions.^[7]

The sandglass is still widely used as the kitchen egg timer; for cooking eggs, a three minute timer is typical,^[8] hence the name "egg timer" for three minute hourglasses. Egg timers are sold widely as souvenirs, and games such as Boggle also make use of it.

Sand timers are also sometimes used in games such as Pictionary to implement a time constraint on players completing an action.

Largest sandglasses

The size of an sandglass is not necessarily the deciding factor for its running time. However, if its running time is to amount to several days or weeks, it will need to be fairly large. Two such giants include the Timewheel in Budapest and the sandglass at the sand museum in the Japanese city of Nima. At eight and six metres in height respectively and a running time of one year, they are among the world's largest chronometers. Another giant has been standing at the Red Square in Moscow since July 2008. At 11.90 m in height and weighing 40 tonnes, this is likely the largest sandglass in the world. By way of comparison the smallest sandglass in the world is just 2.4 cm high. It was made in 1992 in Hamburg and takes slightly less than 5 seconds for a single run through.

Symbolic uses

Pirate Christopher Moody's "Bloody Red" jack, c. 1714

The hourglass, sometimes with the addition of metaphorical wings, is often depicted as a symbol that human existence is fleeting, and that the "sands of time" will run out for every human life.^[9] It was used thus on pirate flags, to strike fear into the hearts of the pirates' victims. In England, hourglasses were sometimes placed in coffins,^[10] and they have graced gravestones for centuries.

Modern symbolic uses

Hourglass cursor

Various computer programs and earlier versions of Windows may change the mouse cursor to an hourglass during a period when the program is in the middle of a task, and may not accept user input. During that period other programs, for example in different windows, may work normally. When a Windows hourglass does not disappear, it suggests a program is in an infinite loop and needs to be terminated, or is waiting for some external event (such as the user inserting a CD).

Hourglass motif

Diagram of "hourglass" motif from carved stone tablet, Solomon Islands

References

Antique sandglasses

Further reading

Books

Periodicals

External links

• Brief History, a detailed history of the invention and construction of hourglasses at hourglasses.com
• Hourglass History, at the site of Tom Young, hourglass maker
• Allegory of Good Government at aiwaz.net

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