BUILDING THAT SHIVER.

New Zealand Herald, Volume LXVIII, Issue 20988, 26 September 1931, Page 7 (Supplement)

BUILDING THAT SHIVER.

SWAY OF SKYSCRAPERS. Ihere is a man in New York whose particular work lias no counterpart' in Britain. He is a consulting engineer, and liis self-appointed task is watching skyscrt pcrs sway and shiver in the wind. It is' pointed out by Popular Science that straige things happen when a stiff breeze hits a structure of forty storeys or more. Office workers sometimes can feel tlie building move, and they may even become seasick. This odd " sky sickness " has been traced to the swaying of objects in the room. Hanging'lights in one New York office building swing several feet, though tho building moves only a fraction of an inch. Tall structures, such as the Empire State building, the Chrysler building and tlie Manhattan Company building in New York are carefully planned so that they can bend without breaking. Architects built the 925-foot Manhatten Company building so that it could swing toward tho fobtpjith as much as two feet in a wind. Equally flexible is the Empire State building, upon which engineers have calculated the wind may exert a total overturning force of 4.2^0,0001 b. Hitherto engineers have planned the ability of skyscrapers to " give " in a wind largely by rule of thumb, with a generously ample margin of safety. But now, as even taller towers are proposed., engineers lor the first time have become acutely conscious that no one has measured, as a guide, the behaviour of tall buildings in a wind. That is where Mr. D. 0. Covle comes in. Not long ago he invented an instrument, patterned after a seismograph, or earthquake detector, to measure and record a building's " shivers " in the wind. Every building that lie 'has observed so far has proved more than adequately safe.

Mr. Covle has ascertained that each skyscraper has an individuality in its response to gusts of wind. The wavy lines recorded on his instrument's chart show that one building often shivers as many as forty times a minute; some of the newer, " slower " towers, as few as eight, ft is these small but repeated vibrations that make lamps swing several feet and waves rise in bath tubs.

From Mr. Covle's records engineers obtain data to aid in planning future towers. On a windy day he takes his machine to the top of a skyscraper, lie levels it exactly with three adjustable screws and sets it in motion. Within the apparatus are two delicately-balanced levers —one to record how far the building moves sideways; the other how much the floor tilts. Each lever carries a, mirror that reflects a beam of light upon a moving roll of photographic paper. When the paper is developed it bears two wavy lines, side by side, showing the building's sideways and tilting movement. THE MOLECULE MACHINE. A pleasing description of the molecule has been given by Professor R. W. Wood, one of the greatest physicists, who has just received the highest honour from the University of Berlin. He spoko of " the exact nature of the piece ol machinery which we call the molecule. ' Atoms and molecules are indeed, compact little machines, bristling with energy, so tiny that man may never see them. Yet their privacy has row been invaded by science to such an extent that book after book can be written about their constitution. * STABS WRITE THEIR RECORDS. Making the stars write their own records ol: events interesting to astronomers is the recent accomplishment of the director of an observatory in China. The feat is brought about by a new application of the photo-electric cell, or electric eye, and involves the construction of an apparatus of extreme delicacy.and sensitivity. To measure, for instance, and record the" minute amount of light reaching the earth from a star, the rays are reflected by a mirror and focused through a condensing lens upon the electric eye, setting up a weak current that is amplified through vacuum tubes until it. can operate ari electro-magnetic relay. This causes n stylus connected to it to write an irregular line on a revolving drum, which represents the variations in light received, while sensitive milliammfeters record current strength. Synchronously an astronomical pendulum clock writes a time curve on the same drum. Other applications are the automatic recording of the meridian passage of any star, saving astronomers tedious night vigils, and the study 1 of blinking stars. These seem to blink because of movements in the upper atmosphere, and the study, of this phenomenon may eventually help to reveal facts of importance to meteorologists.