Practical Uses
Hourglasses were an early dependable, reusable and accurate measure of time. The rate of flow of the sand is independent of the depth in the upper reservoir, and the instrument will not freeze in cold weather.
From the 15th century onwards, they were being used in a 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. 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.
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Famous quotes containing the word practical:
“The ordinary literary man, even though he be an eminent historian, is ill-fitted to be a mentor in affairs of government. For ... things are for the most part very simple in books, and in practical life very complex.”
—Woodrow Wilson (1856–1924)
“Philosophy, certainly, is some account of truths the fragments and very insignificant parts of which man will practice in this workshop; truths infinite and in harmony with infinity, in respect to which the very objects and ends of the so-called practical philosopher will be mere propositions, like the rest.”
—Henry David Thoreau (1817–1862)