Science Siftings

New Zealand Tablet, Volume XXXV, Issue 5, 31 January 1907, Page 35

Science Siftings

By 'Volt f

Bricks and water. Bricks are capable of absorbing about a pint- of\ water each. Owing to this circumstance the captain of a ship that carries a cargo of bricks has' to be careful that the leakage does not go undetected, the .water - being sucked up nearly as fast as it gets -in". A High Bridge. " j '-"■ The train bridge vow building across the Royal Gorge in Colorado, will be the "highest bridge in _the world, — 2,627 feet above the river below. Joist "at the point where this 7 " bridge " is to stand, the abysmal . chasm is only 50 feet wide at the 'bottom and 230 . feet at the top. The rugged opposite walls rise almost vertically. Through this narrow gorge the waters of the stream rush with resistless .force and fury. How Rocks Grow. Rocks do not grow in the sense tihat a plant-" grows. They may increase by accretion, and they may undergo chemical change! The old sea bed, being lifted up, becomes sandstone and limestone. The- volcanic ash and lava strewn over the plains become tufa, -hard enough for building stone. The pebbly ..shore of a river becomes conglomerate. The simple mineral does grow, however, when it takes a crystal form. The sparkling prism of quartz increases from an atom to a crystal as large as a forearm by a process of addition and assimilation, wonderfully slow, but beautifully regular, exactly as crystals of ice form on the window pane. The Balloon Plant. ' """" One of the curious devices of nature for scattering seeds is seen in the balloon plant of • California. The fruit is yellow and is a little larger than an egg. It has the appearance of an empty^ bag, but it contains a watery substance, which evaporates or dries up when the fruit matures, a sort of gas taking its place. This gas is lighter than air, and the fruit flips back and forth in the wind until it .finally breaks loose from its slender _ stem; rises into the * air to a hsAght of from seventy-five to a' hundred feet, and sails away to fall in some 'distant spot and thus extend the growth of its kind. A New Automatic Fire Indicator. A new automatic fire indicator is thus described in ' La Nature of Paris : The ' securitas ' may be placed at any point that needs watching, and serves also to indicate the abnormal heating of such substances as - fats, coal, etc. It is placed on the circuit of an electric bell, which it operates as soon as the temperature rises to a certain point in - the medium whore it is - placed. The apparatus is composed of 'ai lower part . shaped like a hemispherical vessel, closed hermetically by. a diaphragm. This vessel is- surmounted by a cylindrical portion having in its centre an adjustable screw completely isolated and protected by a cover. When the temperature rises, the air in the interior of the vessel expands, the central part of the diaphragm rises and touches the end of ' the adjustable screw. The circuit is --thus closed and the bell rings, giving warning of the danger. Several devices of this kind may be installed in. one establishment en" one bell-circuit. Typewriter for the Blind.M. Dussand, the Frenchman, who has rapidly become known througli a number _of important practical ' inventions, has (! invented a - new typewriter . * .for - the blind which is 1 expected to revolutionise the writing- of blind persons and enable them to write and read in the same manner and under the same conditions as those who can see. They will in' future also need 1 only a single alphabet •instead of two, -as heretofore. The apparatus is supplied with a row of keys, and if one, two, or more of these keys are pressed down with the v fingers # the desired letter or the desired word - appears. This new typewriter, .with keys, is by far the most perfect instrument 'which has ever been offered to the blind . for writing. ; . It can be rapidly operated,-^ and furnishes a regular writing that the'blind can easily read. Another advantage of special importance is that the lines cannot run into each other. Tests have been made at the Ecole Braille fpr the Blind, at Paris, which have given the greatest satisfaction.