*Dials – The Product of Muslims Genius *
UNIVERSAL SUNDIALS for all latitudes used for timekeeping and determination of the times of Salah in 9th century Baghdad.
The Navicula de Venetiis, a universal horary dial used for accurate timekeeping by the Sun and Stars, and could be observed from any latitude, invented in 9th century Baghdad. This was later considered the most sophisticated timekeeping instrument of the Renaissance.
Afterwards, the compass dial, a timekeeping device incorporating both a universal sundial and a magnetic compass, invented by *Ibn al-Shatir* in the 13th century.
Its original meaning was *sundial* and/or *clock dial*, from Latin *diâlis*meaning *daily*, or *concerning the day*, because of its use in telling the time of day.
Modern dial is generally a flat surface, circular or rectangular, with numbers or similar markings on it, used for displaying the setting or output of a timepiece, radio, clock, watch, or measuring instrument. The term may also refer to a movable control* *knob used to change the settings of the controlled instrument, for example, to change the frequency of the radio.
The *sundial*, which measures the time of day by using the sun, was widely used in *ancient times*. A well-constructed sundial can measure local *solar time* with reasonable accuracy, and sundials continued to be used to monitor the performance of clocks until the *modern era*. However, its practical limitations - it requires the sun to shine and does not work at all during the night - encouraged the use of other techniques for measuring time.
*Candle clocks*, and sticks of incense that burn down at approximately predictable speeds have also been used to estimate the passing of time. In an *hourglass*, fine *sand* pours through a tiny hole at a constant rate and indicates a predetermined passage of an arbitrary period of time.
Dial* *indicators, also known as dial* *gauges and probe* *indicators, are instruments used to accurately measure small linear distances, and are frequently used in industrial and mechanical processes. They are named so because the measurement results are displayed in a magnified way by means of a dial.A special variety of the dial indicator is the dial* *test* *indicator (DTI) which is primarily used in machine setups. The DTI measures displacement at an angle of a lever or plunger perpendicular to the axis of the indicator. A regular dial indicator measures linear displacement along that axis.
Dial indicators may be used to check the variation in tolerance during the inspection process of a machined part, measure the deflection of a beam or ring under laboratory conditions, as well as many other situations where a small measurement needs to be registered or indicated. Dial indicators typically measure ranges from 0.25 mm to 300 mm (0.015 in to 12.0 in), with graduations of 0.001 mm to 0.01 mm (metric) or 0.00005 in to 0.001 in (imperial).
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