Detroit Post and Tribune (Detroit, MI), Sep 19, 1883
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The Electric Lights on the Calumet and Hecla - Their Height Above Lake Superior - Latitude and Longitude
It is claimed that the powerful electric lights on the Calumet and Hecla (mine), used for illuminating the surface of the mine, are visible at night to the deck officers of the steamers passing up and down Lake Superior. Mr. Preston C. F. West, mining engineer on the Calumet and Hecla, has kindly furnished us with the following data covering the latitude, longitude and height of the lights, with will aid steamboat captains in locating the position on their charts: Latitude of electric lights, 47 degrees, 15 seconds; longitude of electric lights 88 degrees, 27 seconds.*
The light is 765 feet above Lake Superior, and should be visible from the surface of the water 37 miles, and from the deck of a vessel 15 feet above the water it should be seen 42 miles.
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- *These lat/lon figures are incomplete. As given, the site is well out in the lake, but the mine was probably located in the town of Calumet, MI, (lat. 47.247, lon. -88.453).
The usual method of calculating the distance to the horizon in nautical miles is simple: d=1.17xsquare root of the height of the viewer, where "d" equals distance to horizon in nautical miles. To find how far you can see an object from your height above the water, find the "d" of both heights and add them. So:
* for height of the light, 1.17x27.66(the square root of 765) = 32.36Nm or 37.21 statute miles (Nmx1.15) at the water surface
* for height of the viewer, 1.17x3.87(the square root of 15) = 4.53Nm or 5.2 statute miles at 15 feet
* for the distance between the visible light on top of the tower and the officer on deck = 37.21+5.2 = 42.41 miles! Any lighthouse would envy that!
Or, click on this: http://www.boatsafe.com/tools/horizon.htm .
- Date of Original:
- Sep 19, 1883
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- Dave Swayze
- Copyright Statement:
- Public domain: Copyright has expired according to the applicable Canadian or American laws. No restrictions on use.
Maritime History of the Great Lakes