WORLD OF OTHER DAYS.

New Zealand Herald, Volume LXIX, Issue 21118, 27 February 1932, Page 7 (Supplement)

WORLD OF OTHER DAYS.

A CHILDREN'S GALLERY. Sir Henry Lyon, director of (he Science Museum, Soutii Kensington, London, lias arranged a children's gallery full of colour, light, and movement, and the many little figures of men and animals, and familiar everyday things which relate a world of other days to that of the child of to-day. A series of dioramas tells tho story of transport through tho ages. A piehistoric man is seen hearing easily on his back the carcase of his dead pony. Another pushes his family across a stream on a log. Men of a later age make use of sledges and canoes. Tho Roman use of wheels on splendid roads, tho packhorse of tho Middle Ages, the graceful, rather frail-looking ships of Elizabethan seamen, tho stage coach, and the gallant East Jndiaman of the eighteenth century have all been given a place. Scale models, which may be set in motion by a child, show how man has learned to control the forces of nature and make them serve his needs. A man with rhythmically moving body works on Archimedean screw which raises water from a stream. A camel working a chain of pots by means of a revolving pole shows the early use of animal power, and is followed by other fascinating models illustrating tho conquest of water, wind, steam and electricitv.

Lighting through the ages begins with a firebrand in a cave in which a naked baby sleeps upon an animal's skin thrown upon the ground, and ends in a modern nursery with electric lights and an animal frieze round the walls. A particularly good model in this group is a littlo humble tailor's shop, in which an old man works alone, heating his flat-irons over a Bunsen burner in the unpleasant light of unshaded flames at either end of a horizontal bar hung from the ceiling by an iron rod.

SCIENCE SOLVES A MYSTERY. It has boon announced that after nine years of intensive work, a Canadian scientist, Professor John McLennan, director of (lie physics laboratory of the University of Toronto, has found the answer to a question which has long puzzled the world's greatest brains. The problem is simply: How does an electric current, flow along a wire ? A rough outline of the answer to this question has been known for some time. An electric current consists of a stream of electrons, particles of electricity so tiny that billions of them could find ample room upon the point of the sharpest needle. When one switches on a pocket flash-lamp the number of electrons supplied by the battery every second is represented by the figure 3 followed by eighteen noughts. When an electron enters a wire it charges into an atom, drives out one of its electrons, and takes the batter's place. The expelled electron jostles another atom in the same way, with the result that when one electron enters a wire, one electron, but not the same one. conies out at the other end. Professor McLennan's discovery will lead to the making of wires which are perfect conductors of electricity. Those used at present arc not perfect, and big losses of energy take place in them.

OYSTERS FOR ANAEMIA. A new treatment of anaemia by oysters is described by Messrs. H. Levine, K. E. Remington and I''. B. Cnlp, food research chemists at Charlestown, United States. Recently copper lias been discovered to play an important role in anaemia, supplementing the activity of iron and making it more effective. Analysis of the oyster by these chemists has revealed that it is rich in iron and copper, containing more copper than any food—plant or animal—so far examined. The oyster is also a plentiful source of vitamins. Fifteen milligrams of iron is the average daily requirement for man, and fliis, it is stated, is contained in 4oz. of oysters. NEW CINEMA CAMERA. A new moving picture camera, capable of taking 3000 pictures a second and covering about one-third of a mile of film in three minutes, was demonstrated recently before the College of France by its inventor, Professor Magnan. By means of the camera the movements of the wings of a dragon-fly in flight may b c studied in detail on a screen. Students saw a blue-bottle in flight—its wings move up and down 200 times a second—and films of flying mosquitoes and butterflies.