SCIENCE NOTES.

Western Star, 20 August 1929, Page 3

SCIENCE NOTES.

AUTOMATIC .TRAIN CONTROL

A new automatic train control system has been devised by a .Munich engineer, and is being tried in Germany. A selenium cell, acted upon by light rays emanating from the locomotive cab is used to control the speed of the train. The light successively strikes a series of mirrors placed along tb e track. If there is danger ahead, and the approaching section or block is closed, the rays are transmitted to the selenium cell, which is then made to close an electric circuit that automatically operates the brakes. The arrangement is such that the train is brought to a stop gradually. This is accomplished by varying the distance between the mirrors, so that the speed of the oncoming train is first reduced to about thirty-seven miles, then twentyfive miles, twelve miles, and s 0 mi, until it comes to a halt as the last of the four mirrors is left behind. The mirrors are of special construction and are said to be reliable in all weather.

TO SAVE EYESIGHT. An interesting little device has been made by the General Electric Company for preventing school pupils from working in a had light. The electric lamps in the school room are worked By a switch, and can, of course, be turned on in tbe ordinary way. But the switch is also connected with a photo-electric cell, and when the light falls below a certain strength the cell operates and turns on the lights. If the weather gets cloudy and the l ; ght, dim, or when twilight approaches, the ever-watchful photo-electric cell automatically lights up the school rooms, and thus the pupils have always plenty of light to work in. » : AMBERGRIS WANTED. Among the vanishing items of commerce is listed ambergris, a substance thrown off by whales, and highly prized as a fixative of fine perfumes. The increasing scarcity of whales, and the great distances to the oceanic nbdde of the whales, makes the finding of ambergris more uncertain. In order to stimulate collectors this season advertisements are running in fishing and marine periodicals of the Pacific Coast. Prices offered for ambergris this season run from £2 10s to £4 .an ounce. Only three recorded finds of ambergris were mad e last year on tEe west coast.

‘CAMELS’ IN PLANT KINGDOM

When it comes to living without water, there are ‘camels’ of the plant kingdom as, well as of the animal kingdom, says Dr F. L. Pickett, of the botany department of Washington State College. He has discovered mosses and ferns in the semiarid region of the North-west that will live indefinitely without moisture While the ordinary plant vyill not grow without at least a4or 5 per cent, moisture content, these ferns and mossesj. may have their water content reduced to one-tenth of 1 per cent., and live in this condition indefinitely. ‘Some of these plants, known to have been kept between the leaves of a folder in a perfectly dry state for seven years, began to grow when water was applied,’ Dr Pickett said. ‘There is also a wild onion growing in this section of the country, which conserves its water supply through the dry season by means of a corky layer on the outside of the bulb.’

BLIND CHILDREN ‘SEE’ MUSEUM.

A laudable and interesting 'experiment has, been performed in recent months by the Natural History Museum, South Kensington. For the first time special arrangements were n\ade to acquaint blind children with the museum exhibits. ‘The children are placed round a table, and are allowed tojiandle the specimens, mostly of animals, laid out on it, and ' to move round from one specimen to the next, while the lecturer passes from one to another, talking about the specimens, and giving explanations' suited to the years of the children.’ says the report. 'Groups have come from the various institutions for the BTirid, and have expressed, with almost pathetic enthusiasm, their interest and pleasure in th e demonstrations.’ OLD NEWSPAPER FOR ROOFING. , Next to old razor blades, old newspapers are perhaps the greatest nuisance. Now the United States Bureau of Standards declares that they may be used for roofing; not, of course, in their ordinary state. Newspapers are not now used in felts as suggested, hut tests are being carried'. out to see if and sawdust cannot be put into the material without impairing the life of the felt. The tests so far are promising. ROCKETS FOR SPEED. That he has travelled in a rocket sled at a speed of 249 m.p.h,. or nearly twentv miles an hour faster Ihan Major Segrave’s car, is the .story told .by Herr Max Valier, in an article in the London journal Discovery. The test, which took place at Lake Starenberg on February 9 last, obtained but scant notice in tbe press. Describing it, Herr Valier, says . in part: ‘Following the explosion of tbe fifth series of rockets, tbe speed averaged nearly 235 m.p.h.; the last seventy to seventy-five yards, however, were under brake control, so actually the highest speed was nearly 294 m.p.h.’ The sled and rocket machinery cost but £75.