Page:Popular Science Monthly Volume 90.djvu/691

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Timing the Clouds to Determine the Weather

���The "Comb Nephoscope." It consists of an upright brass rod about nine feet long, bearing at Its upper end a cross-piece to which a number of equidistant vertical spikes are attached. The observer turns the cross-piece until the cloud appears to travel along the line of spikes, and notes the time it takes to pass from spike to spike. This forms a basis from which he reckons

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