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Speed, 100 kms. (62.14 miles).-126.345 k.p.h. (78.5 m.p.h.); U. S. A., Lieut. Geo. R. Henderson, on Navy P N 7-1, (2) 535 h.p. Wright T-2, at Baltimore, October 25, 1924.

200 kms. (124.2 miles).—126.345 k.p.h. (78.5 m.p.h.); as above. Records with 1500 kgs. (3307.5 lbs.) useful load.

Duration.-2 hrs. 18 mins.; U. S. A., Lieut. H. T. Stanley, on F-5-L flying-boat, (2) 400 h.p. “Liberty," at San Diego, June 7, 1923.

Distance.-100 kms. (62.14 miles); U. S. A., Lieut. O. B. Hardison, on Navy P N 7-1, (2) 535 h.p. Wright T-2, at Baltimore, October 25, 1924. Altitude.-2130 m. (6986.4 ft.); France, Lieut. Pelletier d'Oisy, on Blanchard, (2) 300 h.p. Hispano-Suiza, at St. Raphael, April 17, 1924.

Speed.-100 kms. (62.14 miles) -100.100 k.p.h. (62.2 m.p.h.); U. S. A., Lieut. O. B. Hardison, on Navy P N 7-1, (2) 535 h.p. Wright T-2, at Baltimore, October 25, 1924.

Records with 2000 kgs. (4410 lbs.) useful load.

Duration.-1 hr. 49 mins. 11/10 secs.; U. S. A., Lieut. O. B. Hardison, on Navy P N 7-1, (2) 535 h.p. Wright T-2, at Baltimore, October 25, 1924. Distance.-100 kms. (62.14 miles); as above.

Altitude.-1489 m. (4884 ft.); U. S. A., Lieut. H. E. Holland, on F-5-L flying-boat, (2) 400 h.p. "Liberty," at San Diego, June 7, 1923.

Speed.-100 kms. (62.14 miles) -110.100 k.p.h. (68.4 m.p.h.); U. S. A., Lieut. O. B. Hardison, on Navy P N 7-1, (2) 535 h.p. Wright T-2, at Baltimore, October 25, 1924.

CLASS D (GLIders).

Duration.-8 hrs. 4 mins. 50% secs.; France, A. Maneyrol, on Peyret, at Vauville, January 29, 1923.

Distance.-8.100 kms. (5 miles); France, Lieut. Thoret, on Bardin, at Vauville, August 26, 1923.

Altitude.-545 m. (1787.6 ft.); France, Descamps, on Dewoitine, at Biskra, February 7, 1923.

CLASS G (HELICOPTERS).

Distance, in straight line.-736 m. (2414 ft.); France, Pescara, on twinscrew Pescara, 180 h.p. Hispano-Suiza, at Issy, April 18, 1924.

Altitude, with 100 kgs. (220.5 lbs.).—1 m. (3.28 ft.); France, Oehmichen, on Oehmichen, 180 h.p. Rhone, at Arbouans, September 14, 1924.

Ditto, with 200 kgs. (441 lbs.).—1 m. (3.28 ft.); as above.-"Flight," January 29, 1925.

AN OAR-LESS LIFEBOAT.

DESCRIPTION OF THE FLEMING HAND-PROPELLING GEAR FOR SMALL CRAft. In the event of shipwreck the only line of immediate escape is that provided by the ships' lifeboats, and after these have been loaded and safely floated immediate danger is by no means over, for it is essential that the boat increases its distance from the sinking ship as quickly as possible. With the ordinary form of lifeboat, propulsion rests solely with the boat crew-the average landsman with an oar of a lifeboat is more often a danger than a help-and even the boat's crew are apt to be upset by the importance of the situation. A practical solution of the problem is provided by the Fleming hand-propelling gear. The arrangement of this gear is shown by the drawing above, which also illustrates the construction of a standard lifeboat of Alfred Holt & Co.'s design.

This gear consists of a series of vertical levers on each side of the boat fitted at their fulcra, about 12 inches below the top of the air tanks, to the

side of the air-tank casing by brackets. These levers are placed between the thwarts and are hinged just above the fulcra, so that when not in use they stow level with the thwart, and therefore do not interfere with the use of oars. The set of levers on each side of the boat are connected at their lower ends to a fore-and-aft rod, and these fore-and-aft rods are, in turn, connected at the after ends to connecting rods which actuate the crank discs which are fitted to a thwartship shaft. On this thwartship shaft, which is placed under the stern sheets abaft the air tank casings, is a wheel geared to a fore-and-aft shaft carrying the propeller.

In connection with the thwartship shaft is a reversing gear consisting of a ratchet wheel keyed to the thwartship shaft, and two oppositely arranged pawls, one or the other of which is always engaged in the ratchet wheel so that the propeller can revolve in the required direction, ahead or astern. This direction may be changed by operating the pawls, which is done by a rocking lever. The boat is got under way by moving the vertical levers to and fro. The whole of the mechanism is entirely cased in, but in such a manner that it can be removed immediately for inspection.

The Mercantile Marine Department of the Board of Trade have fully approved the invention, and boats so fitted are allowed a reduction of 50 per cent in the number of oars carried. The following are the most important features claimed for this system of propulsion. The control of the boat is entirely in the hands of one person, who controls the rudder and, by the reversing lever referred to, converts the direction of travel at will. Therefore, in a lifeboat fitted with this gear, it is necessary only that one man, or at the most two, should have any knowledge of seamanship; the remainder of the passengers may be either men or women, who are equally capable of working the propelling gear without any previous knowledge or experience. Also, when the boat is afloat and the falls are released, the craft can immediately be put in motion and got away from any imminent danger. Other important features are that, owing to the absence of oars and the necessary working space, an additional number of passengers can be carried comfortably and the craft can easily be kept head on to the sea at all times.

The Blue Funnel Liner Hector is equipped with a lifeboat fitted with the Fleming hand-propelling gear, and at the invitation of the owners, representatives of Lloyd's Register, the Board of Trade, the British Corporation and several shipping companies, visited the vessel at King George V Dock on Thursday, January 22, to witness a demonstration of the gear. The lifeboat was first propelled round the dock by a number of the crew and then, with 42 people aboard, a series of tests were made. It was found that with two people at the levers, one on the port side and the other on the starboard side, the craft could be immediately got under way, and with a man at each lever, eight men in all, a speed of about 4 knots could be maintained. The lifeboat on the Hector was stowed under davits invented by Mr. George Turnbull, of the Blue Funnel Line. Considerable interest was aroused by the efficient working of these davits, which are termed the "oneman davit," and for further details we refer readers to the detailed description which appeared in "Shipbuilding and Shipping Record," June 1, 1922 (page 721). Following the demonstration of the lifeboat, the guests were entertained at lunch on board the Hector by Captain E. Worlidge, Marine Superintendent in London of the Blue Funnel Line. Captain Warden and Captain Millett expressed the thanks of those present for the opportunity of witnessing the demonstration and the hospitality afforded them.

The gear is manufactured and fitted by I. R. Fleming & Co., 227 and 228 Tower Building, Water Street, Liverpool, and it is claimed that any existing lifeboat can be fitted with only slight alteration.-"Shipbuilding and Shipping Record," January 20, 1925.

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CORROSION AND EROSION OF STEAM TURBINE BLADING.

The production of suitable material for turbine blading is a problem of increasing importance, particularly for high-speed turbines. In the "Brown Boveri Review" for December, 1924, Dr. E. Honegger describes a series of experiments on the corrosion and erosion of steam turbine blading; he points out that blades are worn as the result of either corrosion or erosion, or of a combination of both.

In the high-pressure regions of turbines the blades only come into contact with superheated steam, so that the risk of corrosion during operation is slight, and if sufficiently hard material is used there is no erosion. For impulse turbines, 5 per cent nickel steel, and for reaction turbines, brass and similar alloys are satisfactory.

In the low-pressure region the problem becomes much more difficult. The particles of water suspended in the wet steam cause erosion, which may be assisted by corrosion when the material is liable to it. It is with this danger that Dr. Honegger deals.

For low and medium speeds many materials are available; 72/28 brass is very suitable, and, as brass does not rust, such blades can be used for many years without signs of wear. Monel metal is also of great value, as its strength is practically independent of temperature changes, and it is highly resistant to erosion and corrosion.

For blade speeds higher than about 600 feet per second, the choice of a suitable material is more difficult, as erosion increases with the velocity of the blade, and, even after a few hours, brass blading shows signs of wear, and soon breaks down. The back rather than the front of the inlet edge of the blade usually wears, and that part furthest away from the center is most severely attacked; this is due to the fact that the small particles of water suspended in the steam are thrown towards the tips of the moving blades and the roots of the stationary blades by centrifugal action.

Another cause of erosion is the use of higher steam pressures without a corresponding increase in the exhaust pressures. As a result more water is present in the steam, and a greater part of the turbine operates on wet

steam.

It will thus be seen that soft metals such as brass are useless for the last row of blades in limit turbines, and harder materials, such as alloy steels, must be used. The alloys recently developed under the name of "stainless steels" are suitable, as they are highly resistant to corrosion and erosion. Some of these steels, however, are very difficult to work, and, as the blades have to be made with great accuracy, must be rejected on that account.

Messrs. Brown Boveri and Co. have carried out extensive researches on these materials, as compared with brass and Monel metal. In the preliminary tests, the results of which are summarized in the table below, taken from Dr. Honegger's paper, very severe conditions were chosen so as greatly to accelerate the attack on the blade material. Specimens of the various metals selected for test were machined to the form of prisms, the cross section being 10 millimeters square, with surfaces milled and finished on a grinder. They were arranged in front of a steam nozzle, so that the jet impinged on the two faces of the prism, the axis of the jet making an angle of 30 degrees with one face and 60 degrees with the other. (Fig. 1.)

Further tests were carried out on specimens drawn down to blade section and set up so that the steam jet struck the back of the blade at a sharp angle. (Fig. 2.)

Copper lacing wire with a steel core was soldered to some of the blade specimens, hard and soft solder being used alternately. Dry saturated steam at about 140 pounds per square inch was employed, and was expanded in the

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