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KF5JRV > TECH 10.08.16 16:57l 23 Lines 1314 Bytes #-3539 (0) @ WW
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Subj: The Nephoscope
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The Nephoscope
The Nephoscope was invented in the nineteenth-century to measure the altitude,
direction and velocity of clouds. Seventeenth- and eighteenth-century methods
of determining cloud height required triangulation from the ends of two
baselines. Other techniques involved using a map to trace the passage of
cloud-shadows over the countryside, or a camera obscura to measure a cloud's
angular height and bearing from 0º north, (known in astronomy as 'azimuth').
Early nineteenth-century mirror Nephoscopes used a shallow tank of inky water
to reflect the sky and employed the same triangulating technique as the camera
obscura, in which the angle of reflection was used to calculate the height of
a cloud. Unfortunately, the image produced using the reflecting pool was
rather restricted and wind easily disrupted its surface.
In 1846, the French meteorologist G. Aimé incorporated a horizontal mirror
into Nephoscope design, which significantly improved the instrument. Fineman's
Nephoscope, first manufactured in 1886, employed darkened glass and was fitted
with a compass needle. A vertical pointer rotated around the glass edge to be
aligned with a cloud observed in the glass reflection. Engraved on the surface
of the glass, concentric circles functioned as a measurement guide.
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