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Updated: May 9, 2025
The result has been that wind velocities published in many official publications have often been in error by nearly 50%. The other forms of velocity anemometer may be described as belonging to the windmill type. In the Robinson anemometer the axis of rotation is vertical, but with this subdivision the axis of rotation must be parallel to the direction of the wind and therefore horizontal.
So they are not such absolute pigs, after all. There was a scent of Stomatol everywhere. Here comes Amundsen. He has evidently been out taking the meteorological observations, as he holds the anemometer in one hand. I follow him through the passage, and, when no one is looking, take the opportunity of slapping him on the shoulder and saying "A grand lot of boys."
Aurora observations had to be made which no instrument would record, movement of clouds had to be noted in the meteorological log, the snow cleared from the anemometer and so forth, then of course rounds had to be made in case of fire, ponies and dogs visited, the galley fire lit or kept going according to requirements, and so on.
Probably a sphere would prove most useful for a pressure anemometer, since owing to its symmetrical shape it would not require a weathercock. A small light sphere hanging from the end of 30 or 40 ft. of fine sewing cotton has been employed to measure the wind velocity passing over a kite, the tension of the cotton being recorded, and this plan has given satisfactory results.
For a time we were led to suspect that the lift of curved surfaces very little exceeded that of planes of the same size, but further investigation and experiment led to the opinion that the anemometer used by us over-recorded the true velocity of the wind by nearly 15 per cent; that the well-known Smeaton co-efficient of.005 V squared for the wind pressure at 90 degrees is probably too great by at least 20 per cent; that Lilienthal's estimate that the pressure on a curved surface having an angle of incidence of 3 degrees equals.545 of the pressure at go degrees is too large, being nearly 50 per cent greater than very recent experiments of our own with a pressure testing-machine indicate; that the superposition of the surfaces somewhat reduced the lift per square foot, as compared with a single surface of equal area.
Damon, anxiously. "On the contrary, it seems to be increasing," replied Tom, with a glance at the anemometer. "It's nearly ninety miles an hour now." "Then, aided by the propellers, we must be making over a hundred miles an hour." said the inventor. "We are, a hundred and thirty," assented Tom. "We'll be blown across the ocean at this rate," exclaimed Mr. Damon. "Bless my soul!
"Some wind that," murmured Ned, in rather awe-struck tones. "That's so," agreed his chum. "But we'd better help Mr. Damon," for that gentleman was slowly crawling back, not caring to trust himself on his feet, for the wind had actually carried him down by its force. "Bless my anemometer!" he gasped, when Tom and Ned had given him a hand up. "What happened?" "It was the great wind," explained Tom.
By the time all was ready, J. T. Daniels, W. S. Dough and A. D. Etheridge, members of the Kill Devil Life Saving Station; W. C. Brinkley, of Manteo, and Johnny Moore, a boy from Nag's Head, had arrived. We had a "Richards" hand anemometer with which we measured the velocity of the wind.
The other thermometers were all checked from this one. On top of the screen a Robinson's anemometer was screwed. This consisted of an upright rod, to the top of which were pivoted four arms free to revolve in a plane at right angles to it. At the end of these arms hemispherical cups were screwed. These were caught by the wind and the arms revolved at a speed varying with the force of the wind.
Louis is not considered a very windy place, therefore the following table may be a surprise to some. This table was compiled from the complete record of the year 1881, as recorded by the anemometer of the United States Signal Office on the Mutual Life Insurance Building, corner of Sixth and Locust streets, this city.
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