SCIENTIFIC ITMS.

North Otago Times, 3 September 1910, Page 4 (Supplement)

SCIENTIFIC ITMS.

; OUR. DEBT TO CHEMISTRY. . Tho effect of.chsniistry upon civilisation has been 1 greater than that of any'oth'er'science, Medicine ora i to I'licmißtry the discovery of synj- - thetlc drugs and of'anaesthetics, and ; the progress that has been made in the. study of metabolism.. The 20th century promises even to outstrip the 19th in chemical progress, which 'will lie im tho direction of'controlling foodstuffs, applying tho raw materials'in the earth, and refining, of metals. ■ ' ■ SCIENCE OF SHIP. STEERING. The difficulty,-.of keeping a modern steamship on a straight course is nc

slight-one. The helmsman, of courso, steers by' the compass) and a small error on tho compass card would, if continued, carry a fast steamship ;':.many miles out.of her course in a single : day's run. Yet the compass. gives the course more acurately than . tho ship can be steered. Owing to tho deflecting power of the waves and the rolling of the ship, which, if she is of the twin-screw type, causes first one of her propellers and then the other to oxert greater ef-. feet, tho.course is continually shifted a little' this way and that, despite the helm, The only safety is in cor- , reeling tho compass course by frequent observations of the sun,,moon, , and stars. • , • £ MAKING MINUTE MEASURE- ' ° MENTS. 'j With changes 0 f temperature tho balance wheels of watches expand and •contract, giving them a tendency to c run slower or faster, according to tho circumstances. But, by making : them of different' kinds of metal, having different degrees of expansion, with increase of temperature, the effect of their changes on the running ' of watchss may be almost entirely 1 eliminated. In dealing with such a ' problem it is necessary to know the : expansibility of metal employed. AI means .of measuring it 1 is furnished s

by an instrument called a dilatomctcr, in which a system of delicate levers or a chain of gear wheels magnifies the motion of a pointer over a graduated scale hundreds of times At a meeting of the Physical' Society in' London not long ago a dilatometsr was exhibited which had a magnification of 1,500 times, so that the change in the length of a piecq of, steel caused by a single degree of rise or fall of temperature was clearly measured by it. PRINTING BY X-RAYS. / xhsre is a process of printing by X-rays, technically called typoradiograpby, One way 'to prepare the original copy is to print the text with adhesive ink and then dust me- ' tallic powder- over it, which will re- ' main only on the printed characters, , The copy is next bound <up with about fifty thicknesses of sensitized ] paper and subjected 1 to the action of the Rontgcn tube. Twenty blocks of fifty sheets each, it is claimed, can ( be arranged simultaneously t around £ a single tube, producing a thousand ] copies of the original with about ' ten exposure, \