SCIENCE, MECHANICAL INTENTIONS, ETC.

New Zealand Herald, Volume XXXVIII, Issue 11825, 30 November 1901, Page 6 (Supplement)

SCIENCE, MECHANICAL INTENTIONS, ETC.

BALANCE OF PGWEE IX NATURE,

It is curious to observe how frequently the progress of an animal or plant or race, otherwise triumphant, is liable to be checked by the attack of some enemy that appears suddenly, or, at least, often unexpectedly, on the scene. Especially is this event witnessed in the history of the insect, world; and but for the operation of some such principle in Nature we should be in danger of being overwhelmed by certain species, to the exclusion of many other forms. There is no doubt that the insect tribes inflict much damage on crops and fruits, and in many cases render the efforts and works of the farmer and gardener null and void. But, on the whole, the balance of power in Nature is very fairly sustained. There is scarcely a species of animals which does not include in its history a list of particular foes, and the increase of the one race implies the undesirable attentions of the other. This warfare among insects especially, and between insects and birds, and even between insect species and lower plant foes, can be illustrated by numerous examples drawn from the experiences of naturalists. One of the latest observations on this head relates to the Nemesis that follows the trail of the caterpillars known as the " army worms," which in Australia eat up and destroy the wallaby grass. This devastation is disastrous indeed, but the saving clause appears in the person of a certain microscopic fungus. This low plant organism, apparently following on the track of the caterpillars, attacks the insects and kills them off by the thousand. Here the plant routs the animal just as, in the case of the plague of field mice, which devastated not only Greece but also the South of Scotland a few years ago, a certain bacillus or microbe, cultivated, and spread over the fields, afflicted the mice, killed them off, and restored peace to the farmers' souls.—London Chronicle.

THE EYE AT WORK. A very curious device has been invented by which it is possible to determine how many times the eye moves in reading, and how fast the movements are made. The object of the instrument is to show in what cases reading is hurtful to the eyes, and thus to prevent shortsightedness and fatigue. In a test of the instrument recently made the results were curious. A man's eye was first made insensible to pain by an application of holococaine, and then a very light shell, with a hole in the centre, was place"d on the eyeball, and held to it by suction. The shell was connected with light aluminium levers in such a way that the eye movements were traced on a moving sheet of smoked paper. Electrical devices caused the pointer to record not only the movements but the speed of each, and the exact time it took. The tracings show that the eye does not move over a printed line continuously, but by quick jerks of varying length. The eye returns in an unbroken sweep until near the end. when it halts occasionally, as if to get its bearings. The average number of jerk movements in reading a newspaper line is about three. A line slightly less than an inch was read without any movement. — Morning Leader.

OYSTER AND MUSSEL CULTURE. Some French naturalists have recently made suggestions regarding oyster and mussel culture which may possibly be fruitful of improvement. It has been observed that mussels and other molluscs that- have become attached to the hulls of ships and floating buoys grow much more rapidly and to a larger size than when attached to fixed objects. They gTow, in fact, nearly twice as large in about half the time. Experience seems also to show that it comes to the same thing whether the water flows past the mussel or the mussel is drawn through the water. All that is required is movement, which brings with it increased food supplies. M. Tanneguy de Wogan reports that he has tested this principle with gratifying success, substituting light and floating instead of heavy and fixed objects, to which the spat can moor themselves. It has long been thought that the oyster thrives best hear or in the mouth of an estuary, and this is possible, for the double reason that the food is more abundant and the movement of the water more constant. The French experimenter is of opinion that what is required in oyster and mussel culture is " perpetual movement in place of unchanging fixity."

IS THE UNIVERSE INFINITE'' Is the universe infinite? After Sir William Herschel had attempted to sound the depths of creation by his mighty telescopes, and found nothing but world on world, with no sign of an end of space, the first man to examine the problem more critically was the illustrious William Struve. The ether of the celestial spaces has been & subject of speculation from the earliest ages of science, and Struve asked the question whether this fluid might not absorb the light of stars in the most distant regions, and thus render them for ever invisible to the inhabitants of the terrestrial globe. He first showed by an investigation based upon the theory of probability, and following the same lines of inquiry which Cheseaux and Olbers had pursued in 1744 and 1823 respectively, that if the ether be a. perfect fluid, so that no light is lost in propagation, and the universe be of infinite dimensions, the stars being scattered promiscuously throughout immensity, the face of the heavens would necessarily glow like the disc of the sun;the whole heavens would be bright like the points now- occupied by the stars. As the vault of the celestial spheres is in reality comparatively dark, even in the regions occupied by the densest masses of stars, it follows either that the universe is not infinite or that the ether is not a perfect fluid. The light of the more distant stars fails to reach and we_thus miss the empyrean of which the poets have written. If, now, we ask which of these two alternatives is indicated we are reduced to the following answer:— the first place, it is not probable that a fluid like ether, which transmits waves of light and electricity with a finite velocity, is a perfect fluid; and therefore the unfathomable depths of it which fill the heavens would perhaps absorb the light ot the more distant stars. Even if the universe were infinite we could never discover this fact. Besides, we know that all space is abundantly strewn with diffused particles of gaseous or meteoric matter, cosmic dust, which here and there, agglomerated into masses, shine as nebulae; and hence this dark matter, scattered immensity, and often wholly invisible, must absorb a small part of the light of distant star*. The more distant the stars the greater the number of dark masses in our line of vision, and hence the greater the absorption of th.ir light. This cosmic dust alone would finally cut off our vision of objects beyond a certain finite distance. Thus the observed absence of Strnve's empyrean may be explained by three hypotheses : (1) The universe is finite. (2) The universe is infinite, and the imperfectly elastic ether absorbs uniformly (that is. without producing colouration in) the light, and cuts down the magnitude of the more distant stars, so that the vault of the heavens appears comparatively dark even where the' stars are densest. (3) The light of remote stars is obscured by dark cosmic matter diffused more or less abundantly /throughout space. Which of these hypotheses represents Nature, if anv of them does, we have no present means of determining. The writer inclines strongly to the belief that hypotheses 2 and 3 offer an adequate explanation of all known phenomena. While our senses conceive space to be endless it does not follow that the universe is in reality of infinite extent ; much less can the absence ot an empyrean prove that the cosmos is finite, even' to our experience ; for this effect may be due to dust in space, or to the uniform absorption of light by the ether. In the exploration of the sidereal heavens it is found that the more powefnil the telescope the more stars are disclosed ; and hence the practical indications are that in most directions the sidereal system extends on indefinitelv. But the possible uniform extinction of light due to the imperfect elasticity of the luminiferous ether, and the undoubted absorption of light by dark bodies widely diffused into space, seem to preclude for ever a definite answer to the question of the bounds of creation. —Professor See in the Atlantic. PINE ODOUR, The Chasseui Francais states that to obtain in a mom the odour of a pine forest a litre of boiling water should be put into a vessel and a little essence of turpentine added drop by drop. Contagious germs are destroyed by the process, which ought to be carried out twice a day. Consumptive patients are also said to derive benefit from , it.