Progress in Science.

New Zealand Graphic, Volume XLVII, Issue 13, 27 March 1912, Page 45

Progress in Science.

MOST POWERFUL EUROPEAN EXPRESS ENGINE.

Important French Locomotive Development.

THE Chemin de Fer du Nord lias recently introduced into service huge “Baltic” type four-cylinder compound superheater' locomotives for operating the Nord Express, Connecting Paris with Brussels, Berlin, the Baltic seahoard, and St. Petersburg. £rhis international express service ranks its the fastest train service in the wofld, and, with 400 tons coach load, the French engine attains 75 miles per hour, developing in the cylinders about 2000 horse-power. Two engines of the “Baltic” wheel arrangement have been built by the Chemin de Fer du Nord for comparative .working, the only difference being that the first engine, 3.1101, is fitted with ordinary locomotive fire-box and boiler, while the later engine, 3.1102, lias a marine pattern water-tube firebox. This fire-

box was designed by the Nord company’s engineers, although actually constructed at the Creusot Works of the Schneider Company. Both engines are fitted with apparatus for highly superheated steam and the cylinders in each engine are identical. Instead of constructing the ordinary type boiler for saturated steam and placing a water-tube boiler for superheated steam over a simple engine, the Bame system of compounding is here employed in both engines. The previous largest engines in Europe are the “Pacific” type, class 10, of the Belgian State railways, which have four cylinders, each 500 millimeters by 6GO millimetres (.19.68 X 25.98 inches). The new Nord engines have, however, two high-pressure cylinders, 440 millimetres (17.32 inches) by 640 millimetres (25.19 inches) and two low-pressure cylinders 620 millimetres (24.41 inches) by 730 millimetres (28.74 inches). Further, ■while the steam pressure in the Belgian engines is 200 pounds per square inch, the French engines carry a pressure of 227.5 pounds per square inch with direct admission from the boiler to all the cylinders whenever it is found desirable for starting. These French engines, although very much more powerful in starting effort than the Belgian locomotives, are of the •ame weight, loaded and empty, as the latter, but the boilers of the Nord engines have 23 per cent, more heating •urface. The chief interest in these new loco-

motives is the novel solution of the cylinder probem, which has for years past Ibeen an obstacle in the design of very powerful locomotives, the difficulty occurring when specially large engines are necessary, either for low-pressure saturated steam, superheated steam, or extra low-pressures in one-ha-lf of a compound engine. The high-pressure cylinders are mounted outside the frames and drive on the centre pair of the three sets of coupled wheels with cranks set At 90 degrees apart. The low-pressure cylinders are inside the frames and drive on the forward pair of coupled cylinders. The cranks in thia case are also set nt right angles 'to one another, and each high pressure is at 180 degrees from its corresponding lowpressure crank. One of the lowpressure cylinders is set in advance of the other, so as to get the centres of the piston rods close together. Although in-

tended for cylinders working at 80 pounds maximum pressure, this device is applicable to any system of engine with such modification as may be desirable. The driving wheels have a diameter of 6ft S( in and the bogie wheels a diameter of 3ft 41in. The firebox grate is 8.56 feet in length, and 5.3 feet in width, and the grate area is 46 square feet. The total heating surface amounts to 4,394.93 square feet, to which the watertubes and firebox contribute 1,097.95 square feet, and the smoke tubes 2629.6 square feet, while the superheater surface is 667.38 square feet. The boiler barrel has a diameter of 6ft 2}in. The water capacity is 1886 gallons, and the steam capacity 690.8 gallons. The tractive force of these locomotives working compound, is 32,429 pounds, and simple 42,834 pounds. An interesting innovation is the adoption of mechanical stokers. On the Northern Railway the express engines are served with “smalls” and “toutvenant" which, to avoid choking the fire and evolving heavy smoke, must be laid on thinly and witli great frequency. Opening the fire-door frequently is injurious to the tube plate, and tends to lower the temperature of the steam in the superheating pipes. With mechanical stokers these and other objections disappear, the fuel in fine powdery form may be blown into the fire box with suitable tuyeres. In running order, the engine weighs 102 tons, of which 24 tons ia on the

leading bogie, 54 tons on the coupled wheels, and 24 tons on the trailing bogie. The tender is of the standard Nord 8-wheels type, and weighs 56J tons, so that in working order these “Baltic” locomotives have a total weight on rails of 158 J tons. <s> <s> <?> The Paths of the Stars. Mr. A. S. Eddington’s summary of the present state of thought on the shape and movement of the starry universe is of absorbing interest. He attempts first of all to give an idea of the way the stars are sown in the immensity of space. Imagine, says he, a globe of space as large in girth as the earth’s orbit round the sun; then think of a volume a million million times greater, Such a space would contain seventeen stars. Some of those stars are nearly fifty times as bright as the sun; some have not onehundredth part of its brightness—though if we were to take a greater sample of space there would be a greater range, for some stars give 10,006 times the light of the sun. Five of the seventeen stars in the sample selected are brighter than the sun; eleven are fainter, so that the sun stands well above the average. . , Mr. Eddington then turns to the theories of the movements of the stars in space—to Kapteyn’s theory that we have to do with tw'O great streams of stars that have become intermixed; to Schwarzschild’s theory that all are travelling about an ellipsoid with differing velocities; and to Dr. Halm's hypothesis that there may be three drifts of stars. These systems when analysed are not unlike; but on the whole the two-drift theory appears to answer best to the facts. Outside these drifts appear to lie certain

stars, like Orion, which are called helium stars, and which seem to have hardly any motion at all, to belong to no system. They are the young stars, and the view taken of them and of the system to which they belong has been modified by the discovery made by Mr. Campbell, of the Lick Observatory, and described by Mr. Eddington as one of the most startling results of modern astronomy, that the younger stars move more slowly than the later ones. Whence, then, are the movements and the speed of stars derived? To that there is nd answer, except in so far as one is supplied by the highly speculative theory that the whole stellar system is a spiral nebula similar to the many thousands of these objects seen in the sky. If that were true it would open to our imagination a truly magnificent vista of system beyond system—of universe beyond universe — in which the great stellar system of hundreds of millions of stars that we know would be an insignificant unit. Edible Birds' Nests. The uninitiated are apt to think of birds’-nest soup as a most disgusting stew of twigs, feathers, and what not. As a matter of fact, the nest used by the Chinese is a very delicate, semi transparent, gelatinous substance, built by the swallow like birds known as the Salangane. The nests are found in the islands about Siam ar.d the Malay Archipelago, mid the harvest in the year 1909 was 18,000 pounds, valued at over

100,000 dollars. It used to be thought that the nest wan formed of inspissated saliva secreted by the highly-developed glands of the bird. Now it is known that the nest is made of a species of alga, gathered by the bird. The season for harvesting the nests lasts from April until September. It takes three months to build the first nest, and just before the eggs are laid the nest is stolen by the collector. The bird immediately sets about the building of a second nest, taking thirty days for the work. This is also stolen before the 9ggs are laid. The third nest, however, is unmolested, and the birds are permitted to raise their young, after which the nest is taken and sold. The nests are built in most inaccessible spots, among the cliffs along the coast, and the natives must risk their lives to reach them. In preparing birds’-nest soup the nest is washed in cold water and then cooked for eight hours in a closed vessel, after which it is mixed with chicken broth, seasoned and boiled for a quarter of an hour. This dish is considered a great delicacy among the Chinese, and Occidentals who have tried the soup find it very palatable and much resembling chi ken soup. Eyes Change Colour. The possibility of a man's eyes changing colour as the result of a mentaj shock or physical ill-treatment, was the subject of an interesting discussion recently by a number of surgeons in the eye ward of one of the great London hospitals. One of the surgeons stated! ’T't.i’’ Common knowledge that gr.at nhyjtxc», hardships may suddenly turn two iltais

white. The loss of colour here follows oil certain chemical changes, due to disturbances of nutrition, taking place in the tiny particles of colouring matter which gives the hair its colour. “All infants at birth have blue eyes. In some babies immediately alter birth pigment granules begin to develop in the iris. Tims they become brown or black eyed. In others, however, no such pigment formation takes place, and ths eves remain blue or grev throughout life. “If this at present blue-eyed ex convict is really the missing brown eyed banker, a reasonable explanation of the discrepancy in the eye colourings would be that under the stress of physical and mental shock, the colouring matter which had in early life developed in each iris had atrophied or disappeared, leaving the eyes the original blue colouring present at birth." . <jt> y. Hypnotising Crabs. Fishermen, it is said, have long been acquainted with a method of mesmerising lobsters by rubbing them gently along the shell of the buck with the tips of the fingers of one hand, while they are held downwards with the beak resting on .some aolisi substance by the othe?. The lobster becomes torpid, and will remain in n state of trance or hypnotism for a variable length of time. l obsters recover immediately if plunged into sea water, but, adds "The r.cu.,' raba take abci ten minutes to recover.