Science Siftings

New Zealand Tablet, Volume XXXV, Issue 47, 21 November 1907, Page 35

Science Sif tings

By 'Volt*

The First Automatic Machine. That the old Egyptians were clever is undoubted, and as far as can be traced the first automatic machine ever invented was a water-raising device known as -the 'noria.' It consisted of a great wheel some twenty-five feet in diameter, having pots or jars hinged on trunnions at intervals of perhaps two or three feet around its periphery. The lower part was immersed in a stream, which turned it on the same principle as a watermill wheel. As the jars went down they were filled, and, being carried up, at a point near the top, they were tipped, turning on the trunnions' and emptying the water into a trough, which carried it away. Lasting Qualities of Wood. Some interesting experiments have been made to ascertain which wood lasts the longest. It was found that birch and aspen decayed in three years, maple and red beech in five years, and elm and ash in seven years. Oak, Scottish fir, and Weymouth pine decayed to the depth of half an inch in seven years j larch and juniper were uninjured at the end of seven years. In situations so free from moisture that they may be practically called dry, the durability of timber is unlimited. The roof of Westminster Hall is more than four hundred and fifty years old. Water in 'Grinding. Why is water used on a grindstone in sharpening a knife? That is one' of the questions asked on the porch .of a summer hotel recently, and, although several well-informed men and wjbird were in- the little gathering, the only one who could answer it satisfactorily was a fifteen-year-old schoolboy. Here is the explanation he gave : The object in using water is to secure a better contact of the blade with the stone, so that the entire edge of the blade may be smoothly sharpened. The application of water not only fills the little spaces between the particles of stone, but it softens them and thus makes a smoother surfr.ce. If a dry stone were used, the edge of the blade wou'd be rough, for the friction would be unequal. Which Boiled First? There is as much difference in boys as will be found in men, some being quick to observe the importance of common things, and others paying no attention whatever to anything. they meet from day to day. Alfred Brown is the^naine of a boy living in Brooklyn, according to the ' Eaglet He is interested in natural science, but cares very little for stories and poetry. He is what ■ may be termed an original, practical boy, and is constantly on the lookout for 'points,' as he terms it. While he is an ardent student of electricity, having invented many machines and , appliances for his own special use, he devotes much of his time to studying watches, clocks, engines, printing presses, and other useful articles. He is not satisfied simplyj to read about the wonders to be found in ordinary things, but/ he is experimenting at odd times to get practical evidence. Not long ago his mother bought a new kettle-f or the cook, and instantly he went to the kitchen. ' Well, well,' said Mary, ' now what be ye wanting, Master Alfred?' 'I have something to tell you,' he replied. •About what?' * ' About that kettle. If you are in a hurry, you'd better use the old one.' ' Go along with ye 1' said Mary, laughingly. ' Well, let us see," said Alfred. ' Fill the old one and the ne"V one with water, and put them on the stove at the same time. If the water in the old one doesn't begin to boil first I will give you a box of candy.' ~" To gratify the boy Mary followed Alfred's instructions, and to her amazement and chagrin the water in the old kettle began to boil much quicker than that in the new one. llt beats all,' said Mary. ' Now, why is that?' 1 That's very simple,' said Alfred. 'It is because the old kettle is covered with soot, which not only keeps the heat in, but absorbs it quickly from the fire. It takes a new kettle of water longer to get hot because the bottom is clean and bright. Polished metal does not absorb heat, but reflects or throws it off. I read about it one night, and proved it the next day when you were out.'