From Wikipedia, the free encyclopedia

An hourglass, also known as a sandglass or sand timer, is a device for the measurement of time. It consists of two glass bulbs placed one above the other which are connected by a narrow tube. One of the bulbs is usually filled with fine sand which flows through the narrow tube into the bottom bulb at a given rate. Once all the sand has run to the bottom bulb, the device is inverted in order to measure another time period.

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. It is still in use, but typically only ornamentally or when a relatively approximate measurement of time is needed (for example in cooking or board games). For cooking and games the time period will be only a few minutes (for cooking eggs, a three minute timer is typical, hence the nickname eggtimer for three minute hourglasses). Today, hourglass collecting has become a niche but avid hobby for some, with elaborate or antique hourglasses commanding huge prices.

Whilst they are no longer widely use for keeping time, some institutions do maintain them, the Australian parliament uses an hourglass to time certain procedures such as divisions.

Contents 1 History 2 Example use 3 Related terms 4 Appearances in modern works 5 References 6 See also

To construct hourglasses, there is no concrete evidence of their existence in ancient times. Since the hourglass was one of the few reliable methods of measuring time at sea, it has been speculated that it was in use as far back as the 11th century, where it would have complemented the magnetic compass as an aid to navigation.

However, it is not until the 14th century that evidence of their existence was found, appearing in a painting by Ambrogio Lorenzetti 1328. The earliest written records come from the same period and appear in lists of ships stores. 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. They were the first dependable, reusable and reasonably accurate measure of time. The rate of flow of the sand is independent of the depth in the upper reservoir, and the instrument is not liable to freeze.^[1]

The hourglass was often depicted on pirate flags where it symbolised the fact that human existence is fleeting, and in England hourglasses were sometimes placed in coffins to symbolise the fact that the "sands of time" had run out. In literature, references to time measuring devices can represent death. There are images depicting the grim reaper holding an hourglass.

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.

The sandglass is still widely used as the kitchen eggtimer, for which supposed purpose it is sold widely as souvenirs. Many board games also make use of it.

(Slang) A woman with a narrow waist and full hips and bust is said to have an hourglass figure.

Hourglass Model - a project research approach (Trochim, W.M.K, 2005). The hourglass model starts with a broad spectrum for research, focusing in on the required information through the methodology of the project (like the neck of the hourglass), then expands the research in the form of discussion and results.

• In MGM's The Wizard of Oz, the Wicked Witch of the West had an hourglass, with struts in the form of winged griffins. Filled with red sand, the piece was used to add suspense, by counting the time to Dorothy's supposed demise. Later when the witch threw the hourglass in a fit of anger it was revealed to have explosive properties.

• In computer operating systems, an icon of an hourglass has often been used as a mouse pointer when the computer has exceeded its RAM or other system resources, it tells the user to wait a minute while the computer processes all outstanding tasks.

• In Walt Disney's Aladdin, the evil wizard Jafar traps Princess Jasmine inside an enormous hourglass.

• A relatively large hourglass is used by the character Imhotep (played by Arnold Vosloo) in The Mummy Returns while threatening the boy named Alex O'Connell.

• Four giant hourglasses filled with various gems are found in J.K. Rowling's Harry Potter and they are used to record the house points of Hogwarts' four houses.

• In the Harry Potter series, the Time-Turner is a small silver hourglass worn on a chain around the neck. It's a very powerful and dangerous magical item which literally turns back time for the user, one hour per inversion of the glass. Hermione uses it to travel in time to attend all her classes. She and Harry also use it to save Sirius and Buckbeak in Harry Potter and the Prisoner of Azkaban.

• In Ubisoft's Prince of Persia: The Sands of Time and its sequel Warrior Within the Hourglass is an object that is central to the plot.

• In the Philippines, a Golden Hourglass was used for a tele-fantasya, Etheria, continuation of the Encantadia trilogy.

• In Days of Our Lives, the hourglass is the symbolic icon shown in the beginning and end credits.

• In the Area 88 remake, a rebel sniper uses the hourglass as a symbolism when someone's life (The mercenary pilot/base personnel) was already over before shooting him.

• An hourglass will be featured in the upcoming Nintendo DS game, The Legend of Zelda: Phantom Hourglass.

• In the 2001 Liquid Entertainment strategy game Battle Realms, Issyl, a Lotus hero, uses an oversized hourglass as weapon with ability Haste, which fasten nearby allies.

• In the video game Kula World, an hourglass is used as the timer to show players how much time is left on their current levels.

• In the Discworld series, Death's Domain has the Room of Lifetimers, a room filled with the hourglass (lifetimer) of every living being in the world. The room even has a hidden, much smaller room (the size of a cathedral) adjoining it, which contains the lifetimers of the gods.

• Some video games, when levels are timed, have power-ups in the shape of hourglasses. Typically, these add one minute to the clock immediately. An example of this is the original Jazz Jackrabbit game.

• The Catacomb 3D series of computer games features an hourglass-based power-up that freezes all of the action (except for the hero, Petton) until a counter reaches zero (i.e., "100 grains of the Sands of Time," where each grain represents an unstated interval of time.)

• The bands Liquid Tension Experiment and Lamb of God both have songs called Hourglass

• Heroes of Might and Magic III features an hourglass as an in-game artifact, that negates all luck effects in combat.

• In an episode of Batman, the Clock King traps Batman and Robin in a giant hourglass, whereupon they escape by tipping it and running on it in the manner of a hamster wheel.

• Northen Lights by Phillip Pullman = a symbol on the Alethiometer meaning a year etc.

• The Elder Scrolls = An Hourglass is seen being carried by Akatosh.

1. ^ Sundials on the internet Pamphlet on the Leicester Time Trail, by Dr A. A. Mills, Millennium Fellow, Dept of Physics and Astronomy, University of Leicester. See section on the sandglasses. Accessed January 2007

• Mechanics of the sandglass, A A Mills, S Day and S Parkes 1996 Eur. J. Phys. 17 97-109 doi:10.1088/0143-0807/17/3/001 (Available here subscription)

• Water clock
• Timewheel
• Egg timer