United States Merchant Marine Academy - Midships Yearbook (Kings Point, NY)

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Measuring eight and one-half feet in diameter, it is large enough to easily accommodate three men. as % old Fresnel lens, imported from Paris and capable of producing a horizontal beam of 200,000 candlepower with a charted visibility of nineteen miles. The largest lens in the United States is of the hyper- radiant type and is located on Makapuu Point, Hawaii. Situated high above the cliffs of Oahu Island, Makapuu Point Light is passed by all commerce from the west coast of North America bound for Honolulu. So elephantine is the lens, having a diameter of eight and one-half feet, that it can easily accommodate three men. Impressive as it is, the lens used at Makapuu Point is obsolete, having been overshadowed by modern advances in optics and smaller lenses, such as those found in the aerial beacon of St. John’s Light at Mayport, Florida. Using two vertical mirror re- flectors, each containing a thousand watt light bulb, St. John’s Light can develop a 250,000 candlepower beam visible for fifteen miles. This is certainly an indication of the pace of the times. Every seafaring man knows the importance of adequate protection against the failure of any neces- sary piece of equipment on board his ship. The lack of proper standby equipment could, if the time ever called for it, prove fatal. So is the case with light- houses. A light must continue to burn showing all its proper characteristics under the worst possible conditions if it is to aid the mariner. The lighthouse at Montauk Point, typical of many lighthouses, has a unique device to meet just such an emergency. Montauk’s heavy lens rests on a metal disk floating atop a trough of mercury. The great density of mercury makes it suitable to support lenses weighing as much as seven tons, and enables a man to com- pletely rotate the lens by hand with little effort. Located directly below the trough is a small horizon- tal drum of steel cable attached to a heavy weight suspended along the inner wall of the structure. The drum is connected through reduction gears to the rotating disk upon which the lens rests. If the MONTAUK LENS: A variation of the famed Fresnel Lens, the lens at Montauk Lighthouse is capable of producing 200,000 candlepower using only a thousand watt bulb. ST. JOHN’S LIGHT: Modern technology has made possible the use of small lenses to achieve the same candlepower effectiveness as was once obtained using large, hard to handle lenses. This Coast Guardsman is inserting a new thousand watt bulb inside the lower mirror compartment of St. John’s Light. ' 13

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equal upon the high seas. There is no chance for error in close pilot waters, for the misinterpretation of a single light can spell disaster for the unwary mariner. The corrected nautical chart, combined with pub- lished listings of lights and their characteristics, is the mariner’s most trusted friend when in pilot waters. Containing pertinent data about the waters the vessel is navigating, the charts also distinguish the various lights in the area, their characteristics, heights, special fog signals, and if the light is a radio beacon, necessary radio information. Using the chart the navigator keeps a continual running account of the position of his vessel, and determines what courses he must make good to bring her safely into port. As the lights slide by, one by one, the mariner silently praises the wonders and certainty of the modern apparatus and the devoted energies of those men and women who care for them. For centuries the only effective means for providing the light necessary to guide the mariner was the glow and smoke from an open fire. Even as late as 1814, the Tour de Cordauan of the Firth of Forth was lighted in this manner. As helpful as they often were, these lights were far from being efficient and reliable. They turn to smoke in rain and flicker beyond cer- tainty in high winds. Many mariners believed it was better not to show the light at all, rather than to show it irregularly. Gradually, as the discovery of the new world in- creased the volume of waterborne commerce, the need for better lights was apparent. Crude coal and wood burning fires gave way to tallow candles at first, and later to oil blazes of sperm, lard, fish, and colza oils. Experimenting resulted in the chandelier blaze holder in which several oil blazes were positioned about the circumference of the chandelier. Small parabolic reflectors were placed behind each blaze to make the most efficient use of the light. In 1898, the first incandescent oil vapor lamp using kerosene was introduced in France, providing a brilliant beam with a small consumption in fuel. The first electric lamp used in this country was in 1886 with the placing of an arc in the Statue of Liberty. Today the majority of lighthouses in this country use electric power, but there are still many located in remote regions employ- ing oil and acetylene vaporized lamps. Lenses were used as early as 1790 in England, but it was not until 1822 that the French physicist, Augustin Fresnel, developed a revolutionary lens design. As Putnam describes it, it was: a built-up lens comprised of a central spherical lens surrounded by a ring of glass prisms, the central portions of which refract and the outer portions both reflect and refract in the desired direction the light from a single lamp placed at the central focus. Variations of this basic lens are used throughout this country today. The lens at Montauk Point Light Station is, for example, a modern adaptation of the CHARACTERISTICS: The distinctive characteristics of all types of lights can all be broken down into a few simple basic indications, the combinations of which pro- duce the varied displays of many lighthouses. This diagram contains these basic characteristics and their abbreviations as found on nautical charts. MAKAPUU LIGHT: The lens in Makapuu Point Light, Hawaii, is the largest lens in the United States. AIDS TO MARINE NAVIGATION OF THE UNITED STATES CHARACTERISTIC LIGHT PHASES Illustration 11111111111111111111111 unii min ■ I ■ I I II II 11= Symbols and meaning Lights which do not change color Lights which show color variations Phase description F.-Fixed Alt.-Alternat- ing. A continuous steady light. F. FI.-Fixed and flashing. Alt. F. FI = Al- ternating fixed and flashing. A fixed light varied at regular intervals by a flash of greater brill! ance. F. Gp. Fl.= Fixed and group flash- Alt. F. Op. FI.™ Alternating fixed and group flashing. A fixed light varied at regular Intervals by groups of 2 or more flashes of greater brilll ance. FI. — Flashing. Alt. FI.-Alter- nating flash- ing. Showing a single flash at regular Intervals, the duration of light al- ways being less than the duration of dark- ness. Shows not more than 30 flashes per minute. Op. Fl.™ Group flash- ing. Alt. Op. Fl.- Alternating group flash- ing. Showing at regular In- tervals groups of 2 or more flashes. Q k . F 1 = Quick flash- ing. flashes per minute. Shows quick flashes for about 4 seconds, fol- lowed by a dark period of about 4 seconds. I. Qk. FI.™ Interrupted quick flash- ing. Short-long flashing. about 0.4 second, fol- lowed by a long flash of 4 times that dura- tion. Occ.= Occult- ing. Gp. Occ- Group oc- culting. Alt. Oce.- Al- ternating oc- culting. A light totally eclipsed at regular intervals, the duration of light always equal to or greater than the duration of darkness. A light with a group of 2 or more eclipses at regular intervals. Light colors used and abbreviations: W —white, R—red, G-green. 12

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TRANSMITTING GEAR: The increasing dependence upon electronics as an aid to navigation has added a new vitality to the lighthouse. Radio Direction Finding signals are transmitted at specific times by this actuating cam device. The lower cam is used to actuate the fog signal. AUXILIARY GEAR: Lighthouses must be ready to function in spite of every emergency. This auxiliary rotating device rotates the lens as a weight slowly falls within the tower, unwinding the cables as it does. KEEPER AND KEROSENE LANTERN: In an emer- gency, a kerosene lantern may be substituted for an electric bulb. emergency occurs that the beacon cannot be rotated by the electric motor provided, the wire is wound upon the drum raising the weight to the top of the tower. Once released the weight descends to- ward the base of the tower, turning the lens as it progresses downward on its sustained four-hour jour- ney. A small kerosene lantern, substituted for the electric bulb, is then all that is needed to make the lighthouse useful once more. In recent years, the lighthouse has assumed an even greater role than it has held before. Electronics has created a new life for the lighthouse. Electronic navigation is no longer a thing of the future, but a reality of the present. Strategically located light- stations throughout the coasts of the free world transmit electronic data enabling vessels to take radio directional bearings on them. Such signals are actu- ated at certain specified intervals by a complex timing device regulated by one of three IBM clocks, the other two acting as a spare and a check on the clock in use. The actual signals transmitted are produced by a cam device whose axis rotates as a speed regulated by the timing mechanism. Thus, through the marvels of electronics, continuous overlapping radio signals be- tween beacons aid the mariner in coastal and offshore navigation. The world has reached a stage where there is a great deal of emphasis placed on automated instruments and machinery, much of it performing jobs once held by men. Nevertheless, it has become apparent that even with all the advantages machines may have over man, they will never replace him. No matter how complex or useful a machine may be, there must be a man’s skill, ingenuity, and constant care behind its operation. It is for this reason that a vast majority of lighthouses throughout the world still employ the 14