SCIENCE NOTES.

Otago Witness, Issue 2370, 3 August 1899, Page 54

SCIENCE NOTES.

— Tho curious radiation, having much in common with Rontgen rays, that has been found by M. Becquerel to proceed from uranium and some allied metals is the object of a recent inquiry by Sir 'William Crookes, who j)oints out in a communication to the Paris Academy of Sciences, January 16, that the energy of such radiation must come from some hitherto unsuspected source. What keeps up the rays? Kontgen rays cannot be produced unless a vacuum tube be excited by an electric coil. Ordinary light rays require some source of heat to maintain the luminous body in incandescence ; yet these invisible photographic rays proceed continuously from uranium compounds, apparently with no expenditure of energy to maintain them. This seems contrary to all received scientific ideas. Sir William suggests that these metals may possibly act like molecular filters, allowing certain slow-moving atmospheric molecules to pass and stopping the

quicker ones, whose arrested motion would then- become the source of the energy that reappears as " Becquerel " radiation-. . —Mr .William. Rowe, son of Mr John Rowe, of the Board of Trade, has invented an eyeprotector adapted for use on board ships in stormy weather. No human eye can long face ' a storm of rain, hail, or sleet at sea, and when to the force of the wind is added the speed of an Atlantic greyhound steaming head on, and binoculars or telescopes cannot be used becau&e the object glasses of the instrument become obscured by moisture, eyes unprotected often receive blows which in some cases produce temporary blindness. Mr Rowe seems to have carried his inventive energy a little further than others who have laboured in the same direction. Several master mariners and marine superintendents have devised instruments to xwotect the eyes of officers on watch and look-out men, and these have invariably taken the one shape — viz., the use of binoculars with the two object glasses removed, or something akin to this. Mr Rowe's storm shade is designed somewhat in tho same way, but is perfected so as to offord the protection which cruder instruments failed to give. The apparatus has a binocular-like form, and when held to the face the eyes are well protected, and when properly held in position to the face it is impossible for rain or hail to reach the eyes^ no matter how fierce the storm may be. A little wind will reach the eyes from outside, but no rain, hail, or snow disturbs the vision ; and this is a matter of vital importance at sea on some occasions. — Photographic researches which are now well known have revealed much as to Ihe structure of metals and alloys, but a still further insight as to structure in relation to -behaviour has been obtained by Messrs Ewing and Rosenhain. whose results are embodied in a paper recently communicated to the Royal Society. Most metals, when polished and afterwards lightly etched, reveal a structure showing that the metal consists mainly of irregular grains, which ordinarily have well-defined boundaries, and these grains, by suitable lighting, can be seen as nodules, with well-marked crystalline facets. The grains are, it would appear, actual crystals, which are deformed by the crowding and crushing together of the various crs'stal growths. To observe and record the effect of strain on the crystalline grains, several methods were adopted, the most usual course being to mount strips of polished and grained metal on the stage of a microscope having photographic attachments, the metal being then shamed by the steady and controlled pull of a miniature testing machine. In other cases larger bars' were strained by means of a 50-ton testing machine, the microscope being mounted on the bar itself. The chief results, as shown by the photograph, taken at frequent stages, are as follows: — When iron or other metal showing the ordinary granular structure is stretched beyoud the limit of elasticity, sharp black lines appear on the crystalline nodules, these lines 'being substantially straight and parallel on each nodule, but the direction is not the same on all nodules. At first, however, the lines are for the most part transverse to the direction of the pull, but as the stretch becomes considerable the more oblique systems of lines develop. If a piece of metal is very considerably strained, a second system of bands appears on some of the nodules, . and sometimes a third system. The authors regard the bands as being due to slips occurring in the various cleavage systems of the crystals. The slip-bands can be seen quite well if polished, but unetched metal is strained, and although at the outset the nodu-lar-structure is not traceable, this structure becomes obvious when the straining proceeds, as the slip-bands themselves map out the positions of the nodules. The microscopic slipbands can be developed by straining iron, copper, silver, gold, nickel, bismuth, tin, or brass, a ready means being by pinching a bright button of silver or copper in a vice. — Amateur Photographer. — The French Government has had for some months past in its hands a machine which causes no distortion of vipage and produces no scar. The machine has been' named " L'Executioner " by its inventor, M. Francois E&clangon, a well-known scientist and the editor of the Monde Scientifiquo, and is in shape like a fourteenth rentury cavalier's helmet. From the top curves a long hollow bar of steel, dividing near its end into two portions, which face two holes in the helmet near the upper portion. Below the=e eyeholes are also cut several breathing spaces. In the cavity of this bar are placed two cartridges, run on grooves made in the curved bar and attached to long curved needles. In the helmet are two hole* fitted with discs, which can be made to revolve until they come opposite the eyes of the victim. The apparatus is in communication with n battery on the table near by which causes the cartridges to revolve, and at the same time to plunge forward and bury themselves deep in tho frontal lobes of the brain, destroying instantly a large portion of the white matter of the cerebrii'n. Death is instantaneous and painless, and only a simple prick at tho angle of eat-h eye shows how the dead man passed. When the novel device wns first brought ii>to iuo, the witnesses who were jiicsent at tho initial performance experienced severe tension of mind because of the slowness with which the discs covering the eye-holes moved." The physicians held that the entrance of the needles and their passage through the eye would not be followed by any perceptible movement on the part of the victim. When the machinery was set in motion, the people present waited with great anxiety until it clicked and did its work. Tho doctors were right. The culprit (lied without confusion. The electrocution innA* it

even mora awe-inspiring than the .Joetric chair. For the victim for a few seconds hears the plates . covering his eyes revolving. It must seem an eternity as the metal giinds its way along until the open holes £ome into alignment with th 6 needle. The penalty of any crime, it would seem, would be paid in the brief interval. — Every boy tises a slate pencil; but hew many know how they are. made, or that most of their manufacture is done by boys? Slide pencils are not, as once they were, mere sections of slate cut from the rock. r lnio is b«i\y they are made: — First, broken pieces of &"'ate are put into a mortar run by steam, and are crushed to a fine flour. This is thoroughly mixed in a large tub with steatite flour and other materials, the whole making a stiff dough. The dough is kneaded, and is then 'a ken to a table, where it is made into short cylinders. Four of these cylinders are placed in on iron retort, which has a changeable nozzle, so that the size of the pencils may be regulated. In | the retort the material is subjected to great j hydraulic pressure, and is thus pushed through the nozzle in the shape of a long cord. As the cord comes through the nozzle it passes over a knife, and is cut into the desired lengths. The ■ lengths are then dried and afterwards baked. The pencils go from -the kiln to the finishing and packing room-, where the ends are held for an instant under a ra-pidly-revolving emery wheel, .which neatly points them. Finally they are packed in pasteboard boxes, 100 pencils in each box. — A remarkable electric gun has been invented, which is said to be deadly, noiseless, arid smokeless. The model which at present represents the inventor's idea weighs only 71b, but with this' tiny gun the most satisfactory experiments have been made. At a distance,of one mile a target was shattered several times by the explosive contents. At a distance of five miles, in spite of a premature explosion, the target was. also shattered. The velocity of the shot is estimated at five and a-half miles in two seconds. The inventor, who is working at a model which will weigh lewt. is the son of a grocer at Portland, and is only 19 years of age. The Admiralty, it is asserted, have offered £75,000 for the invention, which sum has been refused. — To speak of the waves of the sea setting fire to the cliffs they break on seems absurd. Yet this is what did really happen on the western coast of Ireland. These rocks, which the great Atlantic rollers had for centuries been slowlx breaking down and piercing with great caverns contain in their depths masses ot iron pyrites and alum. At last the water penetrated to these, and a rapid oxidisation took place, which produced a heat fierce enough to set the whole jeliff on fire. For weeks the rocks burned. When the fire died out, great masses of lava and clay burnt to brick were seen, in every direction. — For some time there have been rumours of an electric lamp on an entirely new prin ciple, and the matter took more definite shape when the contrivance was recently exhibited at the.Society of Arts, London. It is known as the Nernst incandescent electric lamp, and its chief peculiarity is that it employs a rod of refractory earth iv place of the usual carbon filament, and that this material is not enclose!! in a glass exhausted of air. The rod is preferably composed of the oxides thoria, zirconia, ytotria, etc., which are employee! in the manufacture of the Welsbacb mantle as used in the incandescent gaslight, and when in a glowing white-hot state emits a most intense light. The arrangement differs from familiar forms of electric lamps in that it requires to be lighted with a spirit flame, or by other means, for the rod does not become a conductoi of the electric ourrent until it has been heated. The now lamp offers svich economies of current in use that it is sure to meet with general adoption provided that the rod is cheap and does not require too frequent renewal.