Scientific

Scientific.

   Spanish brown is obtained from an earth dug out of the ground. 

   Dr. Werner Siemens and the German postmaster general have founded an Electro-Technical Society in Berlin. The former stated at a meeting last week that his new electro-dynamic machine had been so improved by Herr Von Hefner that its action is actually cheaper than the locomotive for short distances. He proposes, therefore, to construct light overhead rails,  along which carriages would be propelled by the new engine, which, as we have above indicated, has been perfected since it was shown at the Berlin industrial exhibition. The dynamic engine is also applicable to locomotives, in order to increase their tractive power. 

    London purple is a substance described by Prof. Riley as very valuable for the destruction of insect pests. It is obtained in the manufacture of aniline dyes. It is composed of  lime and arsenious acid, with about twenty-five percent of carbonaceous matter, which surrounds every atom. Experiments show that it is more valuable than paris green as an insecticide, and a perfect antidote to canker-worm; it kills the worm quickly, and does not injure the plant. It is cheaper than Paris green, being mere refuse, which, from its poisonous nature, was a drug to the manufacturers, and had to be got rid of by dumping long distances out at sea.         

    Prof. Riley states that the phylloxera has established itself in California, in the Sonoma valley, and destroyed hundreds of acres of vines in the most important wine district in the State.The insect appears to have undergone a considerable change in habit, which is steadily spreading from infected centres, but very slowly indeed, compared to its in France. Prof. E. W. Hilgard believes this to be due to the non-appearance of the winged female, as he has not been able to obtain it. No one seems ab!e in this valley to give any suggestion as to how the pest may be successfully fought. Every variety of vine planted n the valley has been attacked and partly or wholly destroyed.

    One of the first questions asked by a person who looks at a microscope is, "What is its power?" and others ask, "What is the highest power ever reached?" Of simple microscopes, or hand-glasses, as they may be termed, one sent to the royal society of England, by Di Tarre, of Naples, was said to magnify 2,500 diameters. It was lent to Baker for trial, but he could make nothing of it, and states his sight was seriously injured by trying to use it. With compound microscopes the highest power ever reached is 100,000 diameters. This was obtained about ten years ago by Dr. Dickinson of New York City. Under such a power a single human blood corpuscle would be over thirty-six inches in diameter, or the size of a small cart-wheel. A human hair thus magnified would rival the giant trees of California, for it would be over forty feet in diameter.  A fly would appear as a monster three-quarters of a mile long, and a claw of a honey-bee would stretch across the widest street and clasp the houses on both sides. Of course, in such a case the whole fly could not be seen under the microscope, as a small part of one of the facets of its compound eye would fill the whole field, so that the "fly" would not appear at all. This power was obtained by artificial means, and all sharp definition was lost; thus for real work of any practical use such a power when obtained is worthless.The highest recorded magnifying power of scientific value was that obtained by Dr. Lionel Beale, who obtained 10,000 diameters with a one-eightieth objective. He uses a long tube in preference to high eye-pieces, and no amplifler.