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372 disappears, and the word back in red letters shows in its place. The pro- peller direction signals are operated by electro magnets, which are con- trolled by switches in the contact boxes, operated by the one way gears already mentioned. Each instrument is provided with two mileage counters; which oper- ate in unison. These counters can be reset to zero at any time, independ- ently of each other. Two counters have been provided to enable the navi- gator to keep the total mileage on one counter and the daily run, or trip run, on the other. The mileage count- ers are operated by computing cams which turn the counter wheels by means of a rack and gear segment, a -ball clutch, and a train of gears. Each dial hand of the instrument is mounted on the end of a shaft. On the other end of the shafts which carry the average revolution dial hands, are mounted the computing cams. Therefore the computing cams rotate with the average dial hands. The curve of the cams corresponds with the speed curve of the ship as given in revolutions per minute. Each rise and advance of the cams will ro- tate the counter wheels the correct distance to register the mileage. In- asmuch as a computing cam is mount- ed on each average revolution dial shaft, each of the two cams will op- erate during alternate minutes in uni- son with the average dial hands, and will be reset to zero with the dial hands. Therefore the cams will alter- nately advance the counters the cor- rect amount each minute, and _ the operation of the counters will be con- tinuous. Advantages of the Propeller Log A great deal of thought, time, and expense has been expended to sim- plify, and standardize this’ instru- ment; with the result that there are comparatively few different parts. This log is a precision instrument. The parts are accurately made, and are of the best workmanship and ma- terial. With the navigator’s log installed on the bridge, the navigator has his ship absolutely in hand, he knows exactly what the propeller speeds are all the time, nor is it necessary to call the engine room for information, he knows constantly whether or not his orders are being carried out. If he rings for the propellers to reverse he knows the exact instant each propeller re- verses; he is never in doubt as to the promptness and accuracy with which his orders are executed. The navigator also has immedi- ately before him, constantly, the ex- MARINE REVIEW act distance the ship has traveled ac- cording to propeller speeds. He no longer is required to figure out the ap- proximate average revolutions per min- ute and estimate the distance traveled, This feature is of inestimable value, especially in thick weather, in pick- ing up landmarks, and making har- bor, and of great assistance in dead reckoning. In the engine room the instrument is of equal value to the engineer in holding his propellers to October, 1925 the required speed. The engineer and the commanding officer both have ex- actly the same accurate, constant in- formation as to what the propellers ‘are doing. There can be no doubt or misunderstanding on that score. This instrument has been thorough- ly tested and proven, during the last two years. It will be shown and dem- onstrated at the American Marine exposition, in New York, during the week of November 9 to 14, 1925. After Five Years Service Motorship Ambassador Makes Successful Trip T IS frequently of interest to hear, from time to time, of motor ships which have been in operation for a number of years, as it brings out the dependable and economical serv- ive which is obtained with a diesel engined vessel. A communication from the West Coast gives some details of the motorship AMBASSADOR, a _ vessel powered with a 360 shaft horse- power Nelseco diesel engine. The AMBASSADOR was built by the Tacoma Shipbuilding Co. in 1919 and has the following specifications. The length MOTORSHIP AMBASSADOR—112 FEET IN LENGTH, 22 WITH ONE 3860 HORSEPOWER 6-CYLINDER 4-CYCLE DIESEL ENGINE over all is 112 feet, the beam over all is 22 feet, and the draft loaded is 10 feet 7 inches. Her gross tonnage is 204, the net tonnage is 122 and of 2500 Miles she has a carrying capacity of 100 tons. On her initial trial trip she devel- oped a speed of 11 knots in light con- dition. Her power equipment consists of one 360 shaft horsepower six cyl- inder, four cycle direct reversible Nelseco engine direct connected to the propeller shaft. The AMBASSADOR was built for the Chichagoff Mining Co., Tacoma, Wash., and was in their service until near the end of 1924, when she was sold. During this period, she was engaged in passenger and general freight carrying and FEET IN BEAM—POWERED rendered valuable service to her owners, especially due to her ability to go long distances on a single fueling. In the North West this is a valuable = * ee Sra ea OE cick ik Na ho TA gg