SCIENCE NOTES.

Otago Witness, Issue 2665, 12 April 1905, Page 68

SCIENCE NOTES.

— A novelist some years ago imagined a world in which, sanitary science having cleared aswfy all the germs of disease, the Golden Age that was ushered in would result in map's decay because of the absence of a struggle for existence. But there will always be present the danger that in sweeping- away a species of bacteria man may be 'purging his surroundings of an organism •which is a friend in disguise. Many bacteria are beneficial, as everyone knows, the 'bactei*ia which break up the rocks, the bacteria which are nitrifying organisms, tie bacteria which feed the roots of leguminous plants. But it has been further suggested %>y Professor Bodin, who holds the chair of Bacteriology at Rennes. l;hat many of the disease-producing bacteria are, too, normally harmless, and are non-parasitic in origin. Just as the mosquito's normal foods face vegetable juices, so the disease-produc-ing bacteria may exist harmlessly outside animal tissues, and may, in short, abandon fcheh- virulent parasitism. Inversely, an inoffensive species — that is to say, one which cannot live in complex organisms like the cells of man — may be capable of acquiring •by a series of successive transformations a ! character that would correspond to the appearance of a new disease. Thus disease "would be really an accident. In this view we might, perhaps, regard all bacteria merely as ferments or "agents of chemical■transforrnation useful at bottom. Professor Bodin's speculations are merely speculations, but the theory is seductive. — The day of the triumph of electric, hydraulic,/and steam engines has dawned, and every naval officer of the British navy ; must be a mechanician. There is no room in the new fleets coming into being for "salt horse" lieutenants. - In a floating fortress, in which, everything is done by machinery, the old sailorman type is out of place. There is no niche for him. It may be that in time we shall have engineer officers flyinjr their flags' in command of British ' fleets. The prospect would have been considered burlesque by the executive officers of a few years ago. but it is now a prospect (says Mr Archibald S. Hurd, in a very interesting and 1 well written article in Cassier's 'Magazine) which is recognised as not only within the realms of possibility but as a probable outcome of the apotheosis of the steam and hydraulic engines and "the electric dynamo at sea. Lord Selborne has definitely stated that he has purposely left the dcor open so that his successor, with full i knowledge of the results of the reforms lately introduced, may act as he thinks fit. j For -the present, the •young officer -who s chooses or is selected for the engineering line has his career fixed for life. If, however, a captain finds that a Nelson has by mistake got into the* engine room, it will be within his pow-er at any time to recommend that he should be shifted to the executive branch. The scheme is still in its infancy. It may be criticised on many •Doints, but now that the British authorities have taken the final step and founded a new establishment for the young cadets at Osborne, as a feeder for the Britannia Coliege, there will be no turning back. It is realised that a change was necessary so as to bring deck officers into sympathy with knowledge of the machinery of the ship; tout the revolution lies not so much in this 1 quarter as in the sweeping away of the | democratic line of engineers and substituting I for them officers of the same social status, j fdeals, and aspirations as their comrades on j the quarterdeck. The existing line is to be retained only until the new line is ready to take its place. This is the most noteworthy j change in the manning of the British Navy i that has ever been carried! out. I

— Even the- humming of the telegraph ■wires is not beyond science's purview. Herr {Bock, of Babenhausen (Hesse), has for some time been carrying on observations of the (humming both of telegraph and telephone ■wires, a.nd has laid down certain rules for •forecasting- weather conditions from them. The humming of wires running east tnd west is said to presage a fall of temperature often 10 or more Lours in advance of th 3 thermometer; the humming of wires aiorth and south advises a rise in temperature almost always several hours in advance of the thermometer. Wires running east and west never hum together with . these arunning north and south, " not even, it ! Se said, -when, as in towns, a north j and south wire may be turned at a right | engle to run east and west. The slowest oscillations of the wires may be seen or felt, but are not audible. The bass notes and the higher tenor we hear but faintly when we stand between two poles. If the ear be pressed against a pole we hear more, especially those notes to which the wooden poJe can most easily respond; sometimes '

a special note, started by the wire at the upper end of the pole, is reinforced by resonance, and that which is only feeble on the wire becomes prominent on the pole. If the wind blows along the wire it naturally brings out a combination of notes different f rom that it produces when blowing transversely; and as the direction of the wind is an indication of the position of cyclones or anti-cyclones, it can be understood that the humming produced might serve as a weather forecast. Herr Bock recommends that the observations of the humming, for which he gives directions in Das Wetter, should be taken at 11 a.m. and 6 p.m., and says that when reinforced by the general meteorological forecasts the results obtained have proved extremely trustworthy.

— A recent number of tha American Machinist contains the address delivered at the annual meeting of the American Society of Mechanical Engineers, by the president, Mr Ambrose Swasey, of Cleveland, OLio, on "Some Refinements of Mechanical Science." One of the most difficult problems which mechanical science has had to face lias been the construction of a n aohme that will divide the circumference of a circl-2 with the extreme precision required for astronomical purposes. Tho closeness with which the circle can be divided depends on the closeness with which a spindle fits in its bearings and on its approach to absolute roundness. Such advances have been made that a spindle 4in in diameter at its largest part, and tapering down to three-quarters of an inch at the foot, can bo made sx> neaily round and be fitted to its bearing with such delicacy that a irovement of ore-thousandi'i of an inch in or out of its bearings will in one case cause it to turn with difficulty, and in the other with perfect freedom. The greatest accuracy so far attainable is one second of arc. On the master plate carried by the spindle a line of onethousandth of an incn wide represents 12 seconds of arc. To divide a circle into two-minute spaces takes 33 hours. The spider lines used in 'telescopic work are generally from the fifth to the seventh of the thousandth of an inch in diameter. In measuring sun spots when the heat is great enough to crack the lenses the spider lines remain uninjured. The thread of tho silkworm is too rough and too coarse to be Used for astronomical purposes. The Rowland engine, made for ruling lines exactly parallel and equidistant, is the nearest io perfection of all the mechanisms yet produced. It was especially made for ruling diffraction gratings on speculum metal. With its aid a. metal surface has been ruled with 160,000 lines, there being about 20,000 to ths inch. But this is not die finest pie^ of work of the kind done, for as many as 45,000 lines have been ruled to tha Inch. The cutting tcol moved by the screws moves with such exactness that the maximum error in the ruling does not exceed the millionth part of an inch. Hundreds of the speculum metal plates have been made- with surfaces either plane or curved, with an not exceeding th© tenth of a wave-length, of light — i.e., l-4Go,oooth of an inch. For Michefson's interferometer refracting; plates were made •with flat surfaces accurate to the twentieth part of a wavelength of light— the most difficult 4 ask of the kind ever attempted. Man can weijh the far-distant stars as in a balance, and meas'ira the heavings of the eternal flood ; and at the other end of the scale (tbe Westminster Gazette* remarks) it is to him an easy task to tell the width of the thread of a spider's web.

— Tha Regina arc lamp manufactoi'y at Cclogne has recently constr.icted a new typo of electric lamp that remedies, it is claimed, the manifold inconveniences of the ordinary arc lamps employed for photographic purposes. This apparatus, with the exceptionally long^ period of 250 hours' lighting with a single carbon, permits, through a proper limitation of the entrance of air, of utilising nearly the whole of the energy in chemically active light. The arc lamp is employed on voltages as high as possible, arid the arc has a length of about 3 in. There is thus obtained a very great number of active luminous rays There is evidently a great saving in the current, and the work, it appears, is done five times as quick. With a current of 4 amperes at 220 volts — that is to say, for an energy of 880 watts, the new lamp is, photographically speaking, as efficient as an ordinary arc lamp that consumes 70.4- amperes at ~35 volts, or 3.872 watts.

— Some good may come out of the undoubted evil that the stonework of the Glasgow Municipal buildings is decaying. The first reason assigned for the- decay was that the amount of sulphuric acid which is distributed by the soft coal smoke of Glasgow was to blame. But there are buildings 50 years old in Glasgow by the side of the crumbled stonework which have remained unaffected, and the stone balustra.de on the summit of the Wallace Monument at Abbey Craig 1 , where the air is as pure as the reputation of Caesar's wife, is rapidly crumbling into sand. "£he opponents of the sulphuric acid theory contend that the true cause of the decay of sandstone is the lack of a sufficiency of carbonate of lime, s-vyhichs -vyhich is the natural cement binding the grains of sand together. When this is the case, rain water percolates, and the grains of sand fall away and decay Bets in. It was shown several years ago in defence of this belief that of the 12 building sandstones used about Glasgow the most durable were those containing the largest I'ioportion of carbonate of iinie, and if that be incontrovertible, the sulphuric acid smoke theory has hardly a leg to stand on. Practical experience (says the Morning Post) teaches that the stones of finer texture, on which rain wa'/sr can with difficulty find a ccijm cS v-intAge, arc the more durable.

and in this respect most of thu limestones have a decided pull over the sandstones. Some of the Irish limestones not to speak of the harder Italian marbles, have shown excellent capacity for resisting the weather. In these cases the texture of the stone has clearly stood it in gcod stead. Not only is the smallest foothold given to the disintegrating power of running and freeing water, but there is little chance of microorganisms securing ground for action. The destructive effect of these minute forces does not seem to have received attention, enough. The action of micro-organisms as a probable cause of premature decay in building stones is well worth investigation. The best artists, it has been said, are the most careful of their materials. It is interesting to note that the statues which have the greatest claim to immortality, the Greek, were carved out of the best weatherresisting marble the world has even 'known. — For many years past it has been an accepted axiom in semi-scientific circles that our moon is a dead world, but Professor Pickering, in Nature, has a mass of facts which show that the moon is far from being dead. He finds that there are three distinct sets of changes on its surface — the first due to continued volcanic action, the second to the appearance of hoar frost, and the third to vegetation. It seems that a few years ago a new crater appeared in the vicinity of Hyginus, while observations of the floor of Plato show the continual coming into existence of new craterlets in that curious area. In the crater of Eratosthenes a brilliant wlyte patch is seen when the lunar day begins. It is then five miles by two, but rapidly dwindles to two small spots under the increasing- heat, just as hoar frost would do. Dark spots, which deepen in colour as the long lunar day passes, are seen on many parts of the surface, and, since they are certainly not due to shadows, it is difficult to see what they can be except vegetation.