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TAE MarRINE REVIEW | 25 'SEARCHLIGHT. PROJECTORS By F. M. Feiker. URING the late Rus- so-Japanese struggle a most striking ob- ject lesson has been afforded of the way in which electricity has taken a place as one of the chief fac- tors in modern war- fare. Indeed the many uses to which : this subtle power has por been put have. made it quite indispensable, both on the battle- field and in naval encounters. The general on land directs the movements of his army by telephone, while at sea, the admiral communicates with his fleet by wireless teleg- raphy, and the officer in the conning tower governs the maneuvers of his individual ship through the agency of electricity. ; Among the varied uses to which electricity is put in warfare, one of the most important is its.application to the searchlight. At night from a captive balloon or a ~hill top, this powerful light sweeps the country in search of the enemy, or illuminates the battlefield while the red- cross detail performs its merciful work in caring for the wounded. On the sea, the searchlight continually flashes -- out across the water scanning the waves for torpedo boats, and enabling the gunner to repel them with the rapid fire guns should any be discovered. Mounted at harbor en- trances and controlled electrically from a dis- tance, the beams from the projector lights pa- trol the bay, and along the shore line giant fingers of light point out the incoming ene- my that the gunners in the coast defenses may find their mark. But searchlights have found a place in the piping times of peace as well as in war. Pas- sengers on the Hudson River night boats find new beauties in the scenery of that historic stream viewed in this electric light. Its beams intensify the natural grandeur of the river shores, vividly con- trasting the lighted portions with the sur- .. rounding darkness. The & same effect is produced = by a searchlight on a mountain top, the view of the surrounding HAND CONTROL PROJECTOR. _ country beneath changing with kaleidoscopic rapidity. More practical uses are found, too, for the searchlight aside from these more aesthetic applications. Dockyards and outdoor construction works of all classes are bril- liantly illuminated vy the same means. This method of f -is of course an essential - lighting concentrates the source of light and enables work to be done as quickly and as well as by day. Certain definite details of construction are essential in searchlights for these purposes to insure the most effi- cient service. Special forms of electric arc Jamps and reflectors are used for projectors. ae te The lamp is a horizontal, automatic form of arc-light, equipped with special de- vices for feeding and reg- ulating the carbons, and a silvered mirror concen- trates the light so pro- duced. Both lamps and mirrors are designed for the hard usage to which all marine apparatus is subjected. The reflector feature in the searchlight and is constructed with the greatest care. Two types of mirrors are used, mangin and the parabolic reflector. Fhe former type is adapted to the smaller sizes of lights, and the parabolic mirror is used in the larger pro- jectors, because of the weight of the glass in the mangin form. The arc is placed at the focus of the mirror, so that the crater carbon faces it, and the light is thus thrown from the mirror, in' 'parallel ravs. That portion of the PROJECTOR. light which might be projected from the negative carbon is prevented from so doing by a device called the obtura- tor which cuts off these unfocussed light rays. This pro- tecting shield also serves the purpose of keeping the arc at the top of the carbons, being constructed for this pur- pose, in the form of a permanent magnet completely en- closing the carbons except at the top where the arc forms. As the carbons are consumed, both are fed automatically . keeping the arc always in the proper focus. -If such an -- adjustment were not provided the reflector beam of light would look in profile, like an hour glass. The mechanism of the lamp, however, adjusts the arc in its proper relation to the mirror and prevents this distortion of the light rays. In general, there are four methods of controlling the horizontal and vertical movements of the projector; name- ly, the hand, rope, pilot house and. electric control sys- PILOT HOUSE CONTROL -tem. In the hand control, used in smaller sizes, the oper- ator stands beside the lamp and directs the light by suitable handles without the aid of levers or other devices. The second method, that of rope control, as the illus- tration shows, combines a system of levers, ropes and -- pulleys, which enables the operator to direct the move- ments of the lamp from a limited distance. Pilot-house - control is a specific application of the searchlight, in which the controlling mechanism is so arranged that the pro- jector may be mounted on the pilot-house. This is a common method of installation, and the illustration shows the arrangement employed. In the fourth mentioned sys- tem, the electric control, two motors are used, one for the vertical, the other for horizontal movements of the projection apparatus. These motors are operated at a distance by means of an electric controller connected to them by a flexible cable. ; CONTINUED ON PAGE 22,