Science Siftings

New Zealand Tablet, 24 August 1911, Page 1659

Science Siftings

By ‘ Volt.’

A Big Undertaking.

Engineers announce that by July, : 1915, the , Keokuk dam, the largest in the world except the As-' souan, will be completed, harnessing the Mississippi. When the waters, guided by engineering craft, pass through thirty turbines, they will generate 250,000 horse-power, enough to light every private and public ) lamp, run every street-car, and turn every factory ' wheel in practically every "Mississippi Valley city from the Saint on the north to the Saint on the south. ; Keokuk will become one of the largest distributing centres in the entire world. Already contracts*have . been signed for the transmission of 60,000 horse-ppwer to St. Louis, 175 miles south, to run the street-cars and light the streets of that city. Negotiations are under way to transmit the power north and south, east and * west, from St. Paul to Memphis and from Chicago to Omaha.

Diamond Cleaving,

The art of the lapidary is one of the most delicate employments of mechanical force known. The practical diamond cutter learns many facts about precious stones which are sealed books even to mineralogists. For instance; it is the lapidaries who have found out that diamonds -coming from different districts, vary remarkably in their degrees of hardness. It appears that the hardest diamonds known come from New South Wales. An unfamiliar fact is that diamonds are made to assume approximately the required shape by slitting and cleaving and by ‘ bruting,’ which is the rubbing of one diamond against another, before they are submitted to the polishing wheel. In cleaving, the diamond is cemented on the end of a wooden stick, and a steel blade is driven with a smart blow in the direction of the natural plane of cleavage. Diamonds that have been cut by the lapidary’s wheel lack some of the brilliance possessed by those that have simply been cleaved.

‘ Khaki Color.’

This cotton stuff has been worn in India by British troops for many years. Its tint was a greenish brown, but it always faded when it was washed with soap. A business man from Manchester, while, travelling in India, happened to fall into conversation with an English officer, who remarked carelessly that the first manufacturer who could produce a cotton drill that would not fade would make his fortune. The young Englishman never forgot this hint. He came home, found a skilful dyer, and with him began the search for an olive dye which, when used on cotton cloth, would not yield to soap or soda. They spent years in these experiments, all of which proved fruitless. One day they found among several scraps of dyed cloth one which retained its color under the most severe tests. The puzzling fact was-that it had been cut from the same piece of cloth and subjected to the same processes as the other scraps, all of which faded. The two experimenters were greatly puzzled, and for months tried in vain to solve the riddle. The one little fragment of khaki was the only one which kept its color against all attacks. By chance one day they found that the dye in which this scrap had been dipped had remained for some time in a metal dish of a peculiar kind. The secret was found. v The metal of the dish, in combination with the chemicals of the dye, had furnished the one thing needful., They tried the experiment with other pieces. The dye held, and their fortunes were made. It was not chance which gave them their success, but the indomitable patience and persistence which pursued the chance, and the intelligence which seized it.