An hourglass (or sandglass, sand timer, sand clock or egg timer) is a device used to measure the passage of time. It comprises two glass bulbs connected vertically by a narrow neck that allows a regulated flow of a substance (historically sand) from the upper bulb to the lower one. Typically the upper and lower bulbs are symmetric so that the hourglass will measure the same duration regardless of orientation. The specific duration of time a given hourglass measures is determined by factors including the quantity and coarseness of the particulate matter, the bulb size, and the neck width. Depictions of an hourglass as a symbol of the passage of time are found in art, especially on tombstones or other monuments, from antiquity to the present day. The form of a winged hourglass has been used as a literal depiction of the well-known idiom 'time flies'. = Antiquity =The origin of the hourglass is unclear. Its predecessor the clepsydra, or water clock, is known to have existed in Babylon and Egypt as early as the 16th century BCE. = Early Middle Ages =There are no records of the hourglass existing in Europe prior to the Early Middle Ages, the first documented example dates from the 8th century CE, crafted by a Frankish monk named Liutprand who served at the cathedral in Chartres, France. But it was not until the 14th century that the hourglass was seen commonly, the earliest firm evidence being a depiction in the 1338 fresco Allegory of Good Government by Ambrogio Lorenzetti. Use of the marine sandglass has been recorded since the 14th century. The written records about it were mostly from logbooks of European ships.
The size of the Philosophy School Home Page Hourglass is 57.38KB.
The resolution of the Philosophy School Home Page Hourglass is 512x512.
Keywords that define Philosophy School Home Page Hourglass are new york school, mbbs, nubbin, school home page, sunray, schools in, pearson active learn, is learning, slingback, learn in, a and p school, and public school, school web sight, photos, treadle, philosophy, education & learning, sandglass, top school, school logo images, hourglass, learning websites for students, png.