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The Rhondda Leader

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SCIENCE NOTES AND GLEANINGS.

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SCIENCE NOTES AND GLEANINGS. IRON passing through a cupola always loses in silicon-; the amount of the loss depends on two Conditions: (1) The amount of oxygen brought In contact with the metal in melting, and (2) the composition of the iron as it goes into the CUDOla. THE SPREAD OF TREE ROOTS. The roots of trees seem to vary in length and spread more than the branches. On moist land the roots of the largest trees go down only from 6ft. to 10ft., but Mr. F. R. Baker mentions that saw-palmetto roots have been taken from a w 11 in Florida at a deptfa of 80i't., and in some of the Florida sand nills roots have been known to descend as much as 100ft. DOING WITHOUT SLEEP. The length of time that it is posaible to keep awake is rather surprising. A Philadelphia physician names a medical man who went with- out sleep for eight days and nights and another who did not go to bed for eighteen days, but got all the sleep he had while on horseback. A third did not sleep for fifteen days and nights, but permanently injured his health. TEMPERATURE AND SUNSPOTS. The belief that temperatures are highest during sunspot minima is opposed by Mr. A. B. MacDowall, who finds evidence that during the last sixty years sunspot maxima have been accompanied in England by the higher tempera- tures. The same meteorologist attempts to prove a connection between barometric pressure and the moon's phases, and between relative humidity and the moon's phases. DISEASES OF TREES. Most diseases of trees are due to fungi which attack roots or trunks and sometimes branches or leaves. The older the tree the more liable it is to be attacked, while wounds open the way for infection. M. Schrenck, a French forester, has been studying these fungous diseases and their remedies, and has learnt many important facts. The forcing of antiseptic salts into railway ties, which are being destroyed by fungi in great numbers, is the best method of preservation yet known. GREAT THIRST OF TREES. It has been computed that if the leaves of an elm tree 60ft. high were spread out on the ground, edge to edge, they would cover live acres of land. These leaves, averaging 7,000,000 to a full-grown tree, will transpire water to the amount of seven tons during the normal Bummer day. Were it not for the ingathering of the stomata during the night a few elms would soon draw oft' all the water from a district. As it is, every market grower knows what elms are like near fruit or market gardens. YEAST FOR SKIN DISEASES. Dr. Dreuw, a German physician, states that in cases of skin disease, such as erysipelas, acne, &c., yeast is a valuable hen lor. It can be applied internally and externally—the latter for preference-and the doctor has made a =oap in which the principal ingredient is yeast. The affected portion may thus be simply washed with the yeast-soap in the ordinary manner, or the suds may be permitted to dry on the skin. The most effective means of application is to allow the soapsuds to dry under a water-tight dressing. HOW TO PRESERVE THE SIGHT. The preservation of the sight is of the utmost importance. The following rules are espr'ciaJIy recommended Avoid sudden changes from dark to brilliant light. Avoid the use of stimulants and drugs which affect the nervous system. Avoid reading when lying down or when mentally and physically exhausted. When the eyes feel tired rest them by looking at objects at a long distance. Pay especial attention to the hygiene of the body, for that which tends to promote the general health acts beneficially on the eye. Old persons should avoid reading much by artificial light, be guarded as to diet, and avoid sitting up late at night. Do not depend on your own judgment in selecting spectacles, but go to a specialist in eyesight. PEOPLE WHO SHOULD NOT SMOKE. M. Delie, a well-known French ear specialist, states that tobacco exercises a direct and selective action upon the auditory nerve, and nicotine brings about circulatory troubles, owing to its exciting action upon the great sympathetic nerve. It also gives rise to, or stimulates, a diminution of the nerves, which ends in inflammation and disease of the auditory nerve. Tobacco should be used in moderation, and practitioners should warn patients in whom there is already auditory trouble that its action is specially harmful" in their case. In persons who are already suffering from arterio-sclerosis (hardening of the blood vessels), or who have a family history of such a condition, it ought to be forbidden, and all the more if they are com- paratively young. THE "TIRED" POISON. Conclusions drawn from practical experiments upon dogs are to the effect that labour of body or of brain causes certain changes in the tissues and blood, and through these changes poison is produced, and it circulates in the blood. Some studies have been made to illustrate this subject on fifty grammar school children who were about to be inflicted with one of those periodical "grinds." Before taking the examination their muscular strength was tested. Each one lifted all he could upon the dynamometer, and the average number of pounds for three trials was recorded as his "strength record." After the examination was over, which lasted two and a-half hours, they made the same endeavour to lift all they could. With two exceptions, none could raise as much as before their intense mental activity. LOW TEMPERATURE EXPERIMENTS. The variation of electric resistance at low temperatures is very great in the case of the pure metals, while with alloys it is usually less. An experiment that shews this is to con- nect a small coil of copper wire forming part of an electric circuit with a mirror galvanometer when the coil is plunged in liquid air the current increases greatly; and in fact its value at-190deg. C. is as much as six times that at zero. This is shewn more clearly by a group of incandescent lamps which have a resistance- coil in series, and thus burn at low redness; when the coil is plunged in liquid air the lamps burn with a bright light. According to researches of Dewar, the resistance diminishes gradually with the temperature, but on arriving at-250deg. C. the diminution becomes less and less, so that the resistance at the absolute zero should be still appreciable. At the boiling tem- perature of liquid hydrogen, Dewar has shewn that the resistance of copper becomes 1-150th the normal value. OUR GIRDLE OF STARS. The universe, so far as we can see it, is a bounded whole, writes Dr. Simon Newcomb in Harper's Magazine, It is surrounded by an immense girdle of stars, which, to our vision, appears as the Milky Way. While we cannot set exact limits to its distance, we may yet con- fidently say that it is bounded. It has uniformities running through its vast extent Could we fly out to distances equal to that of the Milky Way, we should find comparatively few stars beyond the limits of that girdle. It is true that we cannot set any definite limit, and Bay that beyond this nothing exists. What we can say is that the region containing the visible stars has some approximation to a boundary. We may fairly anticipate that each successive generation of astronomers, through coming centuries, will obtain a little more light on the subject-will be enabled to make more definite the boundaries of our system of stars, and to draw more and more probable conclusions as to the existence or non-existence of any object outside of it. The wise investigator of to-day will leave to them the task of putting the lem islt a more positive shape. SAHARAN VOLCANOES. Another feature of the remoter history of the Sahara ha.s been revealed. We know that the desert abounds with traces of an ancient system of irrigation, which the lnte Cardinal Lavigeria contemplated restoring. We also know now, on the authority of the eminent explorers Foureau and Gentil, that the desert is thickly studded with extinct volcanoes, ancient and modern. The basaltic remains of the Grand Erb and the many basaltic peaks of the Adrar are mentioned. But the most remarkable case is that of the Air district, where over a territory of ninety-three miles in extent many volcanic peaks are met with, recent enough to shew the craters well preserved. A NEW MAGNETIC ALLOY. A new magnetic alloy is announced by Herr Gumlich. It contains more than 60 per cent. of copper, 20 per cent, of manganese, 10 per cent. of aluminium, and a trace of lead. It is said to be easily worked, and to have the coercive force of prime cast steel. Its maximum permeability equals that of cast iron, and in- creases considerably with age. Unfortunately it will not stand heating, and a temperature of 165deg. Centigrade permanently strips it of its magnetic properties. For the present, at any rate, these new magnetic metals do not seem likely to displace industrially the compounds of iron.

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