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October, 1910 the horizon can be sighted. The line of sight from the eye of an observer standing on the deck of a ship to the distant horizon remains practically horizontal during the motion of the ship. Say a position is chosen on the starboard end of the bridge at which the eye of the observer will be placed; then mark on a vertical batten at the port end of the bridge the height of the eye above the bridge deck as a point of reference. If the distance be- tween the observer and the batten is d feet, the batten can be graduated for an angle of roll 6 by the formula-- Vertical set-off on batten in feet = ao tan v: In rolling, as in all other observa- tions, accuracy depends upon the care exercised by the observers. The period of roll at sea can be de- termined by watch quite accurately while observing the angle of roll, taking the mean of the times of a number of distinct rolls. Special Information Desired With Re- gard to Waves of Inundation Following Earthquakes. Much valuable information is lost because observers are not generally prepared to make observations on the occurrence of an earthquake, or are. not aware of the points on 'which in- formation is specially desired. The value of experiences is considerably lessened when recorded after a lapse of time from memory, as compared with those recorded at the time of the occurrence. For these reasons the Hydrographic Office would em- phasize for the consideration of all seafaring men the following questions as indicating the particular' observa- tions desired to be made of the waves of inundation. 1. What. interval of time elapsed between the earthquake and the ar- tival of the wave of inundation? 2. What interval of time elapsed between the earthquake and the com- mencement of the draining away of the water of the harbor? 3. By what amount was the depth of the harbor diminished by the re- cession of the waters after the earth- quake? 4. To what distance from the shore did the wave of inundation enter the city or the land bordering the sea? 5. What was the height of the wave of inundation? 6. How many and of what maxi- mum size were the vessels that were stranded by the wave of inundation, and to what distance were they borne inland? 7.-Were there any succeeding "TAE MarRINE. REVIEW waves of inundation, and, if so, what period of time elapsed between the successive waves and what were their height? 8. What was the total time of os- cillation of the sea until it quieted down? A New Alloy A new alloy, called "Duralumin," has been discovered by Messrs. Vickers, Sons & Maxim, shipbuilders, of Barrow-in- Furness. It will be made at Birming- ham, England, and will be on the mar- ket in October. H. 3B, Weeks, the chief chemist of Messrs. Vickers' works, has stated that in the course of investi- gations they had found an alloy which they believed to be superior to anything of its kind hitherto manufactured. The company had decided to manufacture it on a large scale. The alloy, whilst slightly heavier than pure aluminum, is said to be as strong as steel. "It can be rolled, drawn, stamped, extended or torged at suitable temperatures. It is less corrodible than other high aluminum alloys under all the usual tests, and possessed altogether many valuable prop- erties. Messrs. Vickers, Sons & Maxim believe there is bound to be a large de- mand for it, as it is only one-third the weight of brass... The firm have protected this alloy by patents through- out the world. The belief is further expressed that the new metal will rev- olutionize many trades which manufac- ture machinery, etc., where weight of metal is often a great drawback, in order to obtain the necessary strength. Mention is made of the bicycle and motor car trade, and even ship. construc- tion in this connection. Ayudante To remedy the inconvenience and delay which have existed at Callao, owing, among other causes, to the fre- quent inability to secure lighterage for their vessels calling with cargo at that port, the Pacific Steam Navi- gation Co. has provided its agents there with a very neat looking and seaworthy little Thornycroft motor launch, the Ayudante, by means of which they will be in a position to ascertain more promptly than has hitherto been possible, the require- ments of the vessels, the lighters that will be necessary for discharging cargo and to make any arrangements that may be required. The launch will also be used for the numerous other duties of the agents which are usually carried out by oar-propelled boats: Its dimensions are a5 tt by 5. 166 in. with only 18 in. draught. The hull is carvel built of mahogany, and 391 copper sheathed to waterline, to ob- viate the destructive effects on tim- ber of sea water in that part of the world. The motor is one of the new Thornycroft paraffine type, of moderate revolutions, with two cylinders 414 in. diameter by 6-in. stroke, developing 13. Be With this a speed of over 934 miles was attained on trial, as a mean of several runs with and against tide. The power is transmitted through a re- versing gear to a Thornycroft solid bronze three-bladed propeller. The fittings of the boat are com- plete as for a ship's launch, including slings for hanging in davits, brass stanchions and canvas awning, ar- ranged to tilt to either side to allow head room when embarking, oars, row- locks, motor horn, lamps, fenders, anchor cable, bilge pumps, etc. In addition to the tiller a steering wheel is fitted handy to the controlling levers, thereby enabling the boat to be managed by one man. The launch was surveyed during construction by the board of trade and was finally registered at Liverpool under the Merchants' Shipping Act be- _ fore being dispatched to Peru. Steamer with Combination Engines The launch of. the passenger and cargo steamer Rotorua, which took place at the ship yard of Messrs. W. Denny Bros. Dumbarton, recently represents another addition to the number of vessels afloat which are propelled by a .combination of recip- rocating and turbine engines. The vessel, which has been built to the or- der of the New Zealand Shipping Co., is 484 ft. by 62 ft. by 35 ft. In the Rotorua steam is first admitted tu each of two sets of triple expansion engines driving twin-screws, and then passes to a low-pressure center tur- bine driving the center shaft before reaching the condenser. The con- tract for this vessel may be taken as a practical proof of the satisfaction with which the New. Zealand Com- pany regard the performance in ser- vice of the Otaki, the vessel built some two years ago by Messrs. Den- ny, and fitted with the combination system of machinery. The Suez canal shares held by the British government, it is stated by John L. Griffiths, United States consul gen- eral, London, yielded $66,661,718 in in- terest and dividends from 1895 to 1909, inclusive. :