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March, 1919 It is said that when this principle is incorporated in a compass an in- strument is developed that will place itself in the true geographic north and south position. Such a compass is unaffected by anything except the rotation of the earth. Thus, errors due to the natural change in the earth’s magnetic pole, changes due to ore deposits, etc., deviations caused by the heeling of the vessel, errors and deviations on steel vessels caused by local magnetic effects, are auto- matically avoided. The principal parts of the gyro- scopic compass equipment are the master compass, the repeater com- passes, the motor generator and the switch panel. _The master compass, shown in the upper illustration con- tains the mechanism that causes the compass to place itself in a true north and south position. The master com- pass is generally placed below decks in a position protected from the weather. Repeater compasses are used at EVELOPMENT of cranes for D handling material in shipyards and ports has been rapid in re- cent months as war demands have in- creased the need for such equipment. Two types of cranes recently built for these uses by the Orton & Steinbrenner Co., Chicago, are shown in the accom- panying illustrations. The wide gage locomotive crane shown at the left was installed recently at the port of Astoria, Oreg., to facilitate load- ing and unloading cargo. It transfers coal or other bulk material from barge HOW MODERN EQUIPMENT EXPEDITES HANDLING OF HEAVY MATERIAL—AT THE LEFT, WIDE-GAGE LOCOMOTIVE CRANE ON THE DOCKS AT ASTORIA, OREG.—AT THE RIGHT, GANTRY LOCOMOTIVE CRANE ‘or ship hold to dock’ storage, dock storage to hopper, handles lumber to and from decks of barges and per- forms other services. It is designed to travel, hoist, load and swing at the same time. The boom is 85 feet long, with ‘a 4- the steering wheels, in the captain’s cabin and in other positions where it is desirable to refer to the ship’s course frequently. A repeater compass is shown in the lower illustration. The card is illuminated from behind by a light, its brightness being controlled by a switch. The repeater compasses bear the some relation to the master compass that repeater clocks bear to master clocks as installed in hotels and other public buildings. The repeater compasses are operated by the master compass through a simple step-by-step mechan- ism wherein the transmitter turns the cards of the repeater compasses to cause them at. all times to accord with the master compass card. The repeater follows the master with a time lag of only 1/200 of a second and will indicate a departure from the course of 1/6 of a degree; an accuracy not required for practical navigation, A repeater compass may also be from cubic yard clam-shell bucket. The cab is of steel for protection to the opera- tor and machinery, allowing use in any sort of weather. The bucket may be operated at a maximum of 80 feet from the center of the crane. A _ load of 50 tons can be lifted at a radius of AT A DETROIT SHIPYARD THE MARINE REVIEW 165 mounted in a pelorus stand for taking bearings. When a repeater is mounted in this manner, a true bearing can be obtained without reference to any other compass or tables. This is a decided aid when navigating from landfalls or lighthouses. The motor generator utilizes part of the ship’s supply of electrical current, turning this into alternating current for rotating the gyro wheels. Direct current at 20 volts is used for operat- ing the repeater compasses. A _ stand- ard storage battery is provided to give an emergency supply in case the ship’s current fails for any reason: The battery will operate the entire equip- ment for a period of two hours. The switch panel includes a small standard meter for measuring the volt- age and current and several small switches for connecting and discon- necting the repeater compasses. It is said that the apparatus is easy to operate, and that it has given excel- lent results in actual use. 17 feet and 7 tons at an 80-foot radius. The traveling mechanism consists of four sets of standard-gage railroad freight car trucks connected by swivel joints to the corners of the car body. One axle of each truck is driven through a train of equalizing gears to allow travel around a curve of 70-foot radius. The trucks operate on tracks laid 16 feet, center to center. At the right is shown a gantry foe motive crane in service at the Detroit yards of the Great Lakes Engineering Works, where steel ships are under con- | ‘