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SCIENCE NOTES ANDI GLEANINGS.

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SCIENCE NOTES AND I GLEANINGS. FBOFKSSOB RUTHBBFOHD, F.R.S., has found by experiment that the heating effect of radium is largely due to the bombardment of the alpha particles expelled from its mass. Ib. BOMNDKK, of the Australian telegraph service, has traced small perforations in the lead covering of aerial telephone cables to the lame of the Bostrycus jesuitica, a little black insect, and to the Zylopertha, a common insect in Australia. A HEAVY RAINFALL. The heaviest rainfall of short duration ever recorded accurately is said to have occurred at Santiago de Cuba. An English engineer found the rate to be more than four inches an hour, and between seven and ten o'clock in the even- ing a total fall of more than a foot was regis- tered by the gauge. The storm covered nearly 300 square miles, in places being even heavier than at the point where the measurement was thads. LEUCITE. Leucite is a felspar geologically, and a double silicate of alumina and potash chemically, found in certain lavas, notably of Vesuvius and the Roman Campagna, where its grey geometrical crystals attract attention. The Societa Romana Solfati of Rome collects leucite between Frascati and Albano, and between Rome and Naples, to manufacture alum from it. Other magnetic minerals found with it are removed by electro- magnets. Sulphuric acid applied to the leucite yields alum, but in order to purify it the crude alum is dissolved and crystallised. ELECTRICITY FOR FRACTURES. An Italian scientist, Francesco Blasi, has been experimenting on the influence of various electric currents on the knitting of bones. The action of galvanic, static, and faradic currents was tried on fractured bones of rabbits. Although all the currents shewed some beneficial effects, the galvanic current was by all means the most effective; the swelling was quickly reducedt and the union of the bone hastened. After the helpful action of galvanic current had been demonstrated on rabbits, their influence was tried on man. The same" beneficial results were obtained. In one case where the bone had refused to knit for over a month galvanism was applied, and in three weeks the fracture was cured. In cases treated by galvanism there is a noticeable lessening of the usual atrophy and inability to use the part after the removal of the splint. AN OBJECTION T > S1MUY. The spray of the sea which so many delight to find blowing in their faces may not be the bealthbringing agent generally imagined. A foreign correspondent of the Lancet, M. Busquet, has been studying the part which such spray can play in the transmission of disease. It can be carried inland at least for 50 metres, and it also is carried high into the air, so that it will fill with mist houses which are close to the water's edge. On the sea front of one place investigated, where numerous sewers discharge, given a strong wind with thick spray, the usual number of germs in the air is trebled. With a gale blowing the proportion of germs is increased in a still higher ratio, and virulent bacilli coli have been found. These researches shew the necessity for the protection of shores from pollution by sewage, and incidentally destroy yet another of our ideals. THE HUDSON RIVER CANYON. Investigations of the sea bottom of the Atlantic at distances of a hundred miles and more off New York harbour have shewn that part of the old bed of the Hudson-now sub- merged-was at the bottom of a great canyon. At one period in the geological history of the American continent the eastern coast was some 9,000ft. higher than now, and in consequence the Atlantic Ocean was many miles from the present site of New York. The Hudson River on its way to the sea appears to have had for a part of the way a canyon at least 3,800ft. deep, and with a width of less than two miles. The soundings have not been carried out system- atically enough as yet to enable geologists to map all of the topographical features of this ancient river bed, but it is known that nearer its mouth the canyon spread out into a widening valley which probably ran down to the sea. COLD WATER AND POISON. In connection with the subject of water, there is one peculiar property of that liquid with which everyone should be made acquainted, and that is its capacity for absorbing impurities, which increases proportionately the colder it gets. Hence, water that has stood in an in- sufficiently ventilated sleeping chamber all night is not only unpleasant, but positively injurious to drink, since it readily absorbs the poisonous gases given off by respiration and the action of the skin. An ordinary pitcher of water, under such conditions, at a temperature of 60deg., will be found to have absorbed during the night from a pint to a pint and a half of carbonic acid gas, and an increase of ammonia. Ice water is an objectionable drink at all times, but if it is indulged in the vessel containing it should never be left uncovered in sleeping or sitting-rooms, because at freezing- point its capacity for absorbing these 4.1. terious substances is nearly doubled. THE WEIGHT OF CROWDS. In "Molesworth's Pocket-Book" we find it stated that, for rough calculations of the loads on bridges, 1201b. per square foot may be taken for the weight of a crowd of people; while in "Trautwine's Pocket-Book we are told that a suspension bridge should not have a factor of safety of less than three against a load of people, whose weight is taken at 1001b. per square foot, which includes an allowance for wind, and for the crowd being in motion. Many years ago, the engineers of the Chelsea Bridge had a number of picked men placed on the table of a weighing machine, and packed together as closely as possible. It was then found that a load on the table of 841b. per square foot was produced. Professor L. J. Johnson, of Harvard University, has shewn, however, says Engineer- ing, that under certain conditions it is possible to obtain much higher figures than those we have mentioned, for he has carried out experi- ments which shew that a loading of 501b. to 1601b. per square foot may be produced by the weight of an assembled group of persons without undue crowding; and later experiments on similar lines shewed that with a maximum condition of load- ing, or one in which forty picked men were placed on an area of 36 square feet, a load of 181,31b. per square foot was obtained. This is, of course, an extreme figure, and could only be obtained with picked men; and Professor Johnson states that they were all tall and care- fully selected. The men all faced in one direc- tion, a position which favours close packing; but it is a condition of things that might easily occur naturally in a crowd. y KILLING INSECTS BY ELECTRICITY. If criminals and other undesirables are killed by the aid of electricity, it should also be possible, according to the Electrical Magazine, to mete out a like fate to all those insects which, to the annoyance and loss of the farmer, take up their abode in the upper strata of the subsoil. Though, perhaps, no one will deny the theo- retical possibility of electrocuting a beetle or grasshopper, still, perhaps, he will wonder why electricians have not already joined hands with the farmer for putting this valuable ally in his possession. The bodies of insects, and especially of crustaceans, present, relatively speaking, a high electrical resistance, and wet earth is a good conductor of electricity. It is thus obvious that a current of electricity, directed into damp soil, will do but little harm to in- sects dwelling therein. Mr, Helberger, engineer, of Monaco, on working in an open field with electrical machinery, found, on sinking into the ground metal rods connected to a 110-volt dynamo, that all the insects came out into the open air almost directly the current had been passed through the earth. In other experiments an ordinary dynamo is mounted on a stout truck, and is driven by gearing from the wheels of the vehicle itself, so that it does not generate electricity unless the vehicle is in motion. The venerated i. conducted to earth by the 7 metal wheels on the one side, and on the other I to a series of copper-tipped brushes mounted on the rear portion of the cart, and so disposed as to keep their tips a few inches from the surface of the soil without coming into contact with it. Between the electrified earth and the bru hes a continuous shower of sparks to ,-k place, which caused all the unfortunate inhabitants of the upper strata of the earth to meet with as instantaneous a death as if they had been struck by lightning. It will be obvious that if the treatment 1 e sufficiently intense the insects must be utterly destroyed, but that the amount of current necessary to effect the operation would probably be so high with this system as to render it hardly economical.

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