SCIENCE NOTES.

Otago Witness, Issue 2896, 15 September 1909, Page 76

SCIENCE NOTES.

— lightning. -*r Lightning is a huge electric spark following cracks in the atmosphere, is the interesting theory of Professor A. W. Porte*; an 35nglish physicist. It does not take~the well'denned zigzag ootxrae in which it has been so often pictured, and its actual irregular path suggests that the air must be cracked by a x blow of sufficient sharpness, like that, from the powerful electrical discharge.. Though cobbler's wax," iike the air, is an unlikely thing to crack, it splits easily under a sudden blow. — How to Remedy a Sagging Door. — A shed or barn door tint has tagged so that the outer end rubs on the floor, sometimes wearing an arc-shaped groove, can easily be remedied. If it is not desired to reset the hinges on such a door, or tie j tools to do the work are not available, the j door can be raised high enough to prevent its dragging by inserting a washer or two on the pin between the halves of the ning3s. ! „The door can be lifted, carrying the pin j off the hinges with 4be top half, the washers being then put on the pins, and! the door finally replaced in a very short time. — A New Overhead Boring Tool. — A recent patent that should be of particular interest to electricians and plumbers covers a machine for boring holes through \ overhead beams, which dees not require tibe j operator to climb a ladder, bat may be ' operated and directed from the floor. The j machine is mounted on a staff provided witij > foot which rests on the floor, and I&isstaff an*y be adjusted to bring £be boring tool against the ceiling or beam. The tool it. operated by nt-aao* of • Hand erartk* and { the- feed is regulated by a cfo»rn, both within easy reach of fhe .operator. The device is arranged to bore a doable line of holes. — Invisible Inks. — l The most curious of all kinds of invwiUe inks is that from cobalt. It is a very singular phenomenon that the figures taaoed out with this ink may be made to disappear and jeappear at pleasure. This property is peculiar to ink obtained from co- . ©alt, for -all the other kinds are at first • invisible until some substance has been j applied to make them appear; but when j once they hare appeared they remain. To prepare this ink, take raffre, and dissolve it an nitoo-muriatic acid till the acid extracts tfrom it the metallic part of the cobalt, which communicates to the zaffre its blue colour, then dilute the solution, which is rery acrid, with common water. If you .■wrrite with the liquid on paper the cliarac- j Hers wHI be invisible, but Wiheii exposed to " a sufficient degree of -heat they will be- , come green. When tie paper has coled they will disappear. Observe, if -he paper be too much heated, they wiU not disappear ' at all. — Alcohol as Fuel. — The belief that almost immediately the tnarket will be supplied 1 with perfectedengines using alcohol for fuel, *nd that it ,-will be a very simple matter, to convert a gasolene or kerosene engine for the new tfuel, appears to exist pretty much «.yery-, iwher* among users aad prospective users of' "combustion engines. It is true hat zuuny designers are at work on the new problem, and that manufacturers are turning th<ir Attention to the new field, and that engines [will soon be available; while the designers tere working under the immense advantage of having at th© back of them tlie aTmost imnumerable problems of the combustion which have boen solved for ga&lene an>l kerossne. Nevertheless, it is quite proibable that considerable time will be spent before the alcohol engine is developed to Ifche standard of the gasolene or kerosene, fes each fuel presents individual peculiarities. — Skimming Boats. — At a time when so much attention is being given to the design of a successful aeroplane it is not at all surprising ttat naval architects should devote a part of (their research work to the application of I the same principle to boats for^raveiling on the surface of the water Among those who iiave directed a large amount of ability and time to this object is Sir John Thornyeroft, end during the past few days he has had Tunning on the Thames at Chiswick a boats 22ft long, which, under normal conditions. Beams to be a river launch, but is adapted ifor skimming on the surface wben propelled at high' speed. This boat, while nor■jmaily of seven knots speed, can attain a speed of 27 knots in smooth -water, the increase in power being enormously Jess Hum. fis usually the case, -even for suitaoiy-de-feigned hulls immersed under ordinary conditions. • A darge measure of success has Vhus been achieved in the application of the Iprineiple of skimming 'in order to reduce jfnctional and wave-forming resistance. — Curious Effects of Lightning. — When an electric current is passed through a number of persons holding hands jit is generally felt most by those at €Le end »f the chain, and several cases have been recorded ia which only those which may be jailed &c terminals of a aeries of animals Kre damaged. Five horses in a line re- ' wived a stroke of lightning ; only the first md fcbe last were lotted. On another ooca-

tas been

j sion five horses in a stable were struck ; 1 the only one to escape death was the one 'in the centre. Several vemarlotbie -*ocounts | have been leccrded where alternate animals • : of- a series Lave been Tkilled. During a storm ia 1901 lightning entered a stable where there were 20 -cows, and it killed !10 of them. The. first, the third, and so on, were killed, while the second, the fourth, and k> ' on, survived. It is certainly difly ] cult to explain cases such as these, but it | would be unwise to deny the possibility ' of their occurrence. — Fecundity of the Oyster.— According to Mr D. 6. Stead, Director of New South Wales Fisheries, the progeny of two oysters of moderate size, if all matured, would cover the whole surface of New South Wales with a carpet of ' oysters. The spawning of this pair of ! oysters would produce 17 millions of eggs, 1 and at the swine ratio, so the lecturer calculated, the result would cover every inlet on our coast with oysters; and in a few years the voyage to New Zealand would be on foot. The present output in New , South Wales was 14,000 bags, and if the | eggs could be preserved one oyster would ' produce that result single-handled. Mr Stead pointed out that penha-ps half these eggs wejie lost for want of fertilisation, and a large number were swallowed by growing oysters. The enmies of .the oyster, which were enumerated, also accounted for many more. —A Simple Test for Milk.— The Scientific American describes a simple , method of testing the quality of mdlk winch should prove useful. It is so simple that it can be tried by anyone, and requires no costly or complicated apparatus. The- sample I -to be tested w first thoroughly stirred, so i -as to.£six tip the oream with the vest. A i portion is then diluted with 50 times its volume of water. . Holding an ordinary drinking glass with a fairly broad and fiat bottom over a lighted candle in a darkened room, the dilutad milk is to be pottred into the glass, until the eonklie-A&me- is just rendered invisible. The depth of the liquid required to do this is a measure of the parity, or otherwise, of the sample. If it I measures lin, it may be concluded that the milk has not been watered. Really good 1 ! quality milk only gives a depth of |in. If ; the milk has been diluted with hnJf its ! volume of "water a depth of l^in is required ! to render the candle-flame invisible. A depth of 2in indicates dilution with an equal volume of water, or that the milk has been ! partly skimmed. — Boring Square Holes. — Bits for boring square holes have been- on the market for years, but they are adapted I for use only in cutting into wood. The tool bores a round hole, while at rhe same time it cuts out the corners with a cutter, which is fed into the hole without turning. Obviously 6uch a tool will not work in metals, and yet square holes have a wideuse in machinery for keys, wrenches, hand wheels, etc. The present method of making square holes in metals is either to punch them in or cast them, or to drill a round 1 hole and then work it up into the right form with a slotter or shaper. A tool for boring square holes in metals as easily and almost as quickly as a round hole can be bored has recently been devieed by Carl Philgus, a German inventor. Ac described in the Scientific American the body of the drill has the form, in cross section, of a spherical triangle. The triangle is made up of equal arcs, each 6*aruck from the intersection of the other two arcs as a oentiee. Such a triangle will always touch the four sides of a oircumsoribed square, and as the triangle is turned the corners of the triangle will move in a rectangular path, following the sides of the square. — A Wonderful Machine. — One of the largest orders ever given for a oierical labour-saving device, either in Europe or America, has recently been placed by the Prudential Assurance Company with Mr Alexander Clement, the managing director of Addressograph (Ltd.), of 91-92 Shoe lane, London, who has specially invented a machine for them for prepfliring the insurance notices and receipts. Owing to the complications arising from tsie varied and special requirements of how the notices and receipts have to bo filled in, many difficulties bad to be overcome; but the various problems wero solved. Briefly, the new insurance addressograph is entirely automatic, the power being derived from an electric motor of one-third horsepower. It prints on the receipt form or renewal notice all the particulars applying to each individual case, such as the number of the policy, name of insured, amount of premium date when payable, and in addition prints at the bottom of the notice or receipt the full name and address, of fiie insured or the person entitled to receive th» notice, the whole being printed beautifully and accurately at tie rate of 2500 forms per hour —Marvellous Electric Clock. — One of the largest electric docks in existence has just been exhibited. It is a marvel : of beauty and workmanship. The pendulum ! weighs over 30001b. The clock contains 5465 multi-coloured electric bulbs, for which 11,000 connections were necessary and over a mile of wire. In making the connections 1401b of special screws were reauired. The

dial, although it indicates hours, minutes, and seconds, lias no hands. The time in minutes is indicated by 60 series of lights, eaoh series containing 32 globe-covered bulbs radiating from an ornamental centrepiece to tihe outer edge of the dial. Shorter rows of different coloured lights indicate the hour, and these change their position 12 times during eaoh. 60 minutes, or onoe every five minutes. The seconds are shown by 60 lights placed at equal distances around the extreme outer edge of the face. The hour figures are 3ft high, outlined in coloured lights. Each second the illumination in the outer circle of light moves for ; . ward one bulb, and when the dial has bees entirely circled the lights indicating the , minutes also advance, and the hour hand, \ formed by lights, makes its slow journey at five-minute intervals. Despite the huge proportions of the oiock, it has been found that it keeps absolutely correct time, even to the second. ! — Chemical Industries. — : The stock example of what neglect of chemistry will do >s, of course, the manu- , facture of artificial dyes. England onoe had the monopoly of dye manufacture, and strengthened her position enormously by the ! discovery, through Perkin, of the coal-tar dye, which was called after 'him Perkio's mauve, and the subsequent amplifications of the aniline derivatives by Hoffman. Then, under the soporific . of success, our- manufacturers let Germany fad .France encroach on their advantage, and though 'tbe^FrancoGerman war gave back tike chemical dye trade to England once more even this stroke of fortune was <us useless as it "was undeserved, for after, the wax Germany once again won - b&ck 4he industry . Germany has never ] lost 'it einoe^ and never will, for there, the importance of science to industry is never underrated. But interesting as this example may be, there is one aspect of it which is sometimes forgotten. It « that ■' the discovery which was of such advantage ' to industry wee made by a pure chemist, who, long before the manufacturers had fully seized on the commercial possibilities of his idea, placidly returned to his laboratory and to the pursuit of, chemical research for its own sake. That is what the nations (and England is by no means the only sinner) fail to understand — that science is pursued by its greatest men with no object but to acquire knowledge, and without regaid to the profits it may bring. For no knowledge ever proves useless, and this page might be filled with instances, culled from the life of Pasteur, of Liebig, of Davy, and of other great chemists, where a discovery apparently of merely academic interest has led to results of tiie greatest importance to mankind's physical well-being. —To Supersede the Stop Watch.— j ! We (Popular Science Sittings) are in a position to five particulars of an invention for operating in daylight wnieh will be as terrible to motor oar malefactors of the road as the Be.rtillon system -and the telegraph are _to ordinary criminals. The deadly invention consists of a double lens camera, .fitted with «i split second' chronometer. The v operator waits until the whizeing machine has passed, presenting its back and the number board. It tafces no expert to make two snaps at the back , of « speeding ear, and if the second image is one-third as large as the first, the motor mast have- been 50ft further from the' lens. Suppose the ascertained distance to be 581 ft, while the chronometer registers a full second of time, the speed of the motor is proved to be 40 miles an hour. '