SCIENCE OF THE DAY.

New Zealand Herald, Volume LXIV, Issue 19798, 19 November 1927, Page 5 (Supplement)

SCIENCE OF THE DAY.

SIZE OF BIRDS' WINGS* A problem which from tlio first has called for intense study in aeronautics lias been tho finding of an answer to " Why do small birds have to havo larger wings than big ones?" and "Why do they have to move their larger wings more rapidly ?" says Dr. Austin H. Clark, of the Smithsonian Institution, at Washington. "It is a curious fact," says Dr. Clark, " that the larger the animal the smaller, in proportion are the wings." " Small birds have relatively larger wings than, big ones," he remarks, " and insects have relatively much larger wings than birds. In a butterfly of the average size," ho says, " each pound of body weight represents a %vinged area of three square yards, eight square feet, and 87 square inches. In tho swallow this is reduced to only four square feet and 18 inches, and i.u the stork to only 122 square inches. Small birds also niovo their wings more rapidly than larger ones," says Dr. Clark. Tho wing of the humming bird vibrates so rapidly that it is difficult to register it. Tho wing beats of the sparrow are 780 per minute, of tho pigeon 480, and of the crow about 120. Two functions aro porformod for a bird by its wings; by them it is lifted from the ground and also is propelled. It has been demonstrated," Dr. Clark points out, " that if a light object is thrown, it will not travel so far as a heavier object thrown at tho same speed. When a largo and heavy bird once gets started, a relatively small, force will keep hiin going. The lighter and smaller a bird the less momentum is acquired. Wings of largo and heavy birds serve chiefly to maintain speed, while the wings of small light birds must constantly lift tho bird and drag it forward. Large birds, however, while thoy fly with much less effort, have greater difficulty in stopping," says Dr. Clark.,

THE MYSTERIOUS ELEMENT. If it bo true that the deep spring which has been found by borings at Runcorn, England, far below t"ho Mersey, is impregnated with radium to an exceptional degree, the discovery may be of the greatest importance, says a London paper. Radium is the most activo element known.

Neither of its curative nor of its destructive powers have the limits yet been found. It is only known that it will sometimes cure and sometimes cause the most terrible, of all diseases; that if 0110 could harness the energy of one ounce of the pare metal, it would suffice to drive the Mauretania two or three times round the world; but that for any human being to enter the room in which that ounce was kept would be certain death. It is known, also, that it has the strange property of endowing other things, particularly water, with its own astonishing nature. TESTING OF CLOTH. Selecting suitable cloths for suits of all kinds has been mado so scientific of late that it seems that, in the future, overy tailor will have his own laboratory, where ho can test materials in the same way that a dispenser tests drugs. < With a number of specially constructed instruments, experiments have recently been carried out to test the resistance of fabrics to various degrees of heat, wind, and exposure. The apparatus used for testing heated retention consists of an electrically heated square-metal plate, on both sides of which samples of the material under observation are clamped down. To this is attached a meter which records the temperature of the plate and the amount of heat required to keej) it at that temperature. PREHISTORIC BONES. A discovery which is believed to bo of considerable scientific importance has been made by workmen engaged in dredging the bed of the River Meurthe at Nancy, in France. Among the debris brought to the surface was a number of bones which could not have belonged to any kind of animal now in existence. Dr. Based, a specialist in prehistoric research, after a detailed examination of the bones, which, by the way, aro in an excellent state of preservation, has expressed the opinion that they form part of the skeleton of a brontosaurus.