Science Siftings

New Zealand Tablet, Volume XXXV, Issue 15, 11 April 1907, Page 35

Science Siftings

By 'Volt 1

Sound of the Human Voice. No- man knows the sound of his own voice. He" hears himself through two channels — the outer- ear "and the- eustachian tube.. He hears his friend through the .ear only : hence he would rather listen to himself than to" his friend. Try your voice in a gramophone. At first you will not recognise it, but you will immediately identify that ,o£ your friend. Mahogany Bridge. A bridge built entirely of mahogany," claimed to be the only one of the kind in the- world, is in the State of Chiapas, Mexico. The bridge spans 1 the Rtio Michol, and its total' length, including- approaches, exceeds 150 ft, while the widthr is 15ft. It is ' used ■by , both teams and pedestrians, and, though somewhat rude and primitive in construction, is very substantial. None of- the timbers of the flooring were sawn, for in that region there are no sawmills, but were - hewn and split. . Disease-Breeding Insects. It is contended by scientific experts that the mysterious and dreadful sleeping sickness peculiar to certain, reigdjons in - Africa is carried, if not caused 1 by the" bite of the terrible tsetse fly. It has been -de- ■ monstrated that the mosquito carries the germ of yellow fever/ Now comes Dr. W. J. Goodhue, who announces that after years of research he has demonstrated that the bacillus of leprosy is spread by the cimex lectularius, which is the technical name of the ordinary bedbug. Dr. Good-hue is the medical superintendent of the Molokai leper settlement. To a Hair's Breadth. Major McMahon made some interesting statements in a lecture on standards in weights c and" measures" at the" .Royal Institute recently. A platinum bar at" Palace yard is so accurate that it can be . used to measure microns which are the 25,000 th part of '-an inch. The balance at King's yard is so sensitive that when a 20 ft weight was placed in each scale and one grain was added to one of them," the •beam oscillated for twenty-six hours. When, the balance at the Paris bureau is used the operation takes place six or seven yards away from it, and. the readings are made through a telescope in order to prevent inacouracy arising from the heat of the operator's body. . Centenary of Steam Navigation, 'It is of great interest to recall that this year is the centenary ,of "steam navigation on a commercially successful basis,' said the president of the Engineering "Association of New South Wales, in addressing that body the other day. *It was in 1807 that Robert Fultoni built and firsf'ran on "the Hudson River the steamer " Olermont," which made the first really successful voyage by steam from New York to Albany, a distance of 150 miles, in 32 hours against current and wind. The " Clermont " was 133 ft long, 18ft beam, and 9ft deep. It was fitted with paddle engines made in England by Boulton and Watt, and said to be 20 horse-power. The* new Canard liners " Lusitania '-' and. il Mauritania " are .785 ft long, 88ft beam-, 60ft in- depth, with . a displacement of 43,000 tons, and a total inuics, ted' horse-power of.6B,uuu. _ The World's Railways. ..Nearly half' the railway mileage of the globe (533,000 miles) lies within the confines of the Ignited States of America, viz M 212,350 miles.- How insignificant in comparison ■ are Continental pretensions in this direction is revealed- toy-, the fact that Russia and Germany, tying for second place, . have only 34,130 and 34,000 miles respectively to, their credit. India, Aus-tro-Hungary, and France are all the superiors of the United Kingdom, which can only boast .of 22,634 miles oJ metals. Regarding gross receipts, however, Great Britain occupies a more enviable position. While the United States totals a sum of £395,uuu,uuO, with receipts per mile £1,860, Great Britain can boast of £111,800,000, with receipts per mile £4,940 ; and Russia's gross receipts, with about 12,000 more miles' of line . than . tUe United Kingdom" possesses, reach lessthan a third of the figure.