by Terry-Pepper » February 19, 2012, 11:42 pm
Tibbetts Point was outfitted with a fixed Fourth-Order Fresnel lens. As such, it did not rotate, but merely exhibited a constant white light. After electrification in 1931, the characteristic was modified to occulting white every ten seconds, by merely installing a timer which automatically switched the electric lamp on and off. That same lens is still in the lantern, and exhibits the same occulting characteristic to this day. As such, there are no beams - just a "flash"
tark9m is 100% correct. By design, the Fresnel lens concentrates 95% its light horizontally, and with a focal plane of approximately 50 feet above the base of the tower, you would not see very much light until you were a considerable distance away.
Tibbetts Point was outfitted with a fixed Fourth-Order Fresnel lens. As such, it did not rotate, but merely exhibited a constant white light. After electrification in 1931, the characteristic was modified to occulting white every ten seconds, by merely installing a timer which automatically switched the electric lamp on and off. That same lens is still in the lantern, and exhibits the same occulting characteristic to this day. As such, there are no beams - just a "flash"
tark9m is 100% correct. By design, the Fresnel lens concentrates 95% its light horizontally, and with a focal plane of approximately 50 feet above the base of the tower, you would not see very much light until you were a considerable distance away.