SCIENCE SIFTINGS

New Zealand Tablet, 22 August 1918, Page 46

SCIENCE SIFTINGS

By “Volt.”

Not Real Mahogany. i The name “mahogany” is applied commercially to more than 50 different woods. Perhaps half the lumber now sold under that name is not true mahogany, for the demand greatly exceeds the supply (states Popular Science Monthly)., The tree is only native to the limited area between southern Florida and northern South America. Nowhere else does it really flourish. But the public will have mahogany. Women want it for furniture, business men prefer it for office fixtures, and teak and mahogany are rivals in the affections of shipbuilders. Therefore substitutes flourish. It is not suppi ising that the real wood is so expensive when it is learned that it takes from one hundred to one hundred and fifty years for a mahogany tree to reach merchantable size. Most of the substitutes bear little more than a general resemblance to the genuine wood, but skilful finishing makes them very much alike. Experts can usually distinguish between them by the aid of an ordinary pocket lens. The efforts of the superficial, however, to judge the wood by its appearance, weight, grain, and color often lead them astray.

A Geographical Problem. Evidences of the elevation of New Zealand within recent geographical times were discussed by Dr J Henderson in a paper read before the Wellington Philosophical Institute recently. Dr. Henderson expressed the opinion that New Zealand as a whole had changed its level at various times. There had been periods when the level had fallen, but he did not think that there had been much local variation. The raised beaches that were found all around New Zealand proved, in hie opinion that the whole country had risen and fallen, He drew attention specially to levels that might be called the 100 ft, 250 ft, and 500 ft strand lines, and mentioned that there was evidence of a small rise, a few feet only, within quite recent times. He quoted a mass of evidence bearing on the subject. Dr. C. A. Cotton, in the course of the discussion that followed the reading of the paper, said he disagreed with Dr. Henderson regarding the nature of the movement that had taken place. He believed that there had been a great deal of differential movement. His observations had led him to believe that the levels of the raised beaches were by no means regular. Mr. G. Hogben said it was hard to believe that so large an area of land could rise and fall without local variations. He mentioned the evidence that the big earthquake of 1855 raised the level ot the land in Wellington and neighboring districts. Later Mr. Hogben - read a paper dealing with the earthquakes experienced in New Zealand during the years 1914 to 1917 inclusive. He said that the movements all had their origin in fault lines situated beneath the ocean from 180 to 250 miles east of New Zealand, and extending roughly from the longitude of Kaikoura to that of East Cape. The disturbances must have been very severe to make themselves felt in New Zealand.