SCIENCE and INVENTIONS.

New Zealand Herald, Volume LVI, Issue 17139, 19 April 1919, Page 3 (Supplement)

SCIENCE and INVENTIONS.

GREATER AIR SPEED. A contrivance has been invenlted enabling aeroplanes to fly at a rate un-herd of hitherto and at heights previously considered impossible. The engine, which is based on the principle of the turbine, is designed Ito produce 30,000 revolutions a minute. The invention also comprises a small ventilator fpr the purpose of compressing the air at great heights at which [the instrument is used. It is said to be thus possible to furnish the engine with compressed air at the pressure usual nearer the ground. This invention, ilt is claimed, will enable a flight from Paris to Cairo, approximately 1965 miles, to be made in 11 hours.

films AEROPLANE CAMERA. The ordinary camera has a "focal length," or distance between the centre of the lens and the plate, of from 7 to 10 or 12 inches. But before the armistice was signed perfect lenses had been made, having a focal length of fifty inches and having a diameter of ten- inches. Equipped with a camera of this enormous size, the lens protruding through the botitom of the fuselago of his aeroplane, the aerial observer can fly at a height of three miles or more and with an exposure of a five-hundredth of a second) or even less, make a picture of the ground beneath so full of detail that tho (trained experts at the laboratory behind his own lines can detoct even the footprints that show where the men had marched over the damp earth the night before.

WORLD'S FINEST TESTING TANK. The model testing tank at Washington is now declared to be the finest of its kind in existence, having a total length of 500 feet and a water surface breadth of 24 feet. The object of these novel basins with Itheir intricate and delicate machinery is to ascertain tho correct design of a warship or liner; that is to say, what should be her size to obtain a given speed. A model of the proposed ship is first fashioned in wax. It is then attached to a travelling platform and towed through the water alt varying speeds. For instance, tho wax model of the hull of the ship 10 feet long is tested. It is possible to asceiltain how a ship 200, 250, 300 or more feet in length would behave if designed upon this model, the power neces- ' sary to obtain certain speeds, etc. Our own admiralty has a tank alt Haslar, near Portsmouth.

MACHINE FOR PICKING COTTON. One of the latest labour-saving devices hailing from America is a machine for picking cotton. The apparatus works on the principle of the well-known vacuumcleaner, nozzles having a powerful suction being applied to the Dolls or pods,' which they completely clear of their cotton and seeds., A high-speed centrifugal fan creates the suction in th« hose-pipes leading to the nozzles, of which there are five. 'The cotton, together with leaves, twigs, and other foreign matter sucked up by the nozzles, is -drawn into the centre of the fan, and expelled at the periphery into a large pipe, which starts in an upward direction and curves round to the back of the machine, where the cotton is discharged into bags, the heavier foreign matter having being thrown out en route through perforations in the pipe. Cleaner cotlton is turned out by this machine than that picked by hand.

TYPES OF DEPTH-BOMBS. One of' the first type of depth-bombs to be used in submarine warfare was operated on a float-and-line principle. A floait detached itself from tie charge proper upon striking tne water and remained on the" surface, while the charge sank, and in sinking payed out rope attached to the i float; when a predetermined length of rope had run out the charge exploded. The latest type, however, has on its lop ft dial containing an indicator with figures like the face of a watoh. When the indicator is turned to a certain number that number denotes the feet beneath the surface at which the charge will explode. As the indicator is turned a reservoir is automatically opened, the water in which increases its pressure on the detonator as the charge descends. When the reservoir is full the detonator acts and explodes the charge. This depth-bomb is discharged by means of a specially-constructed gun.

'COMMERCIAL MOTOR TRUCES. The motor truck of two tons capacity has, up till the present, represented the maximum commercial use of pneumatio tyres. But lately, means were found to overcome the difficulties of producing large-size pneumatic tyres, and although still more or less in the experimental stages, trials have demonstrated the practicability of driving five and even seven ton trucks, fully loaded, at speeds which I would put to shame the best efforts of a, touring car of a few years ago. Recently a severe experimental trip was made with two trucks across the American continent from Boston to San Francisco and return by way of Los Angeles and the Santa Fe trail. This trip was successful in every respect and demonstrated that a fully loaded five-ton truck could be expected to negotiate roads open to the average touring car. The total distance covered was 8520 miles, and the average speed maintained during the running time was l<ty miles an hour.

WATER-POWER IN INDIA. A scheme has now been undertaken for utilising the heavy rainfall in the hills adjacent Ho Bombay for supplying power to the city in the form of electricity. Provision for a continuous supply- of water-power all the year round was rendered particularly difficult owing to the fact that the rainy season Lists for only three months; hence enough water has to be stored !to maintain .the supply for the other nine. Three lakes have been formed by building masonry dams, one of which is close on 100 feet in height, and extends for 1 i miles. One of the lakes maintains the supply of water during "breaks" in the monsoon, while the other two have a capacity of 10.000,000,000 cubic feet, or approximately 50 per cent, in excess of the quantity needed to keep the powerfftation running at its full output during the dry season. Power derived from this source will cost less than that from coal, oil or vegetable spirit; while, aftor doing its jvork at the power-house, the water will\still be available for irrigation.

GOAL-SAVER FOR OPEN FIRES. When coal is burnt in an open fire most of the heat goes to waste, a large proportion passing up the chimney. In order to trap some of the wasted heat in the easiest possible manner, the apparatus, described as follows, has been devised: — Alt each side of the hearth is a vertical cylinder, supported on three legs, and containing a smaller cylinder inside it, the space between the inner and outer tubes being closed at the top and torn. A steel chamber, fitted into the fireplace above the fire, has a horizontal diaphragm dividing it into an upper and a lower part From the lower part of the chamber a pipe is led to each cylinder, and the hot gasetfrom the fire, being unable to go straight up the chimney owing to the diaphragm, aro compelled to traverse one or other of the two pipes loading into the cylinders Here they are forced Ho circulate through the space between the inner and outer tubes by moans of suitable baffles, and are finally roturned through a pipe to the upper part of tho chamber, and thence into tho chimnoy. The inner tubes of the upright cylinders are open at the top and bottom; hence, when Ithey become heated, a constant current of wanned air issues from the top of each, while cold air enters at the bottom. It was found in a room containing the apparatus that the increase of temperature was from twice to fully thrice as much as in a room containing » coal fire without tbo apparatus, |