Page:Popular Science Monthly Volume 13.djvu/268

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on March 20th. He was born in 1814; studied medicine at Tübingen and in Paris; in 1840 he visited the Dutch East Indies, and while there was led to study the relation between heat and work. His first publication on this subject appeared in 1842. In 1871 he was awarded the Copley medal by the London Royal Society.

The Colorado potato-beetle is reported to have made its appearance in New Zealand, where it now exists in formidable numbers in some localities. It appears to have been introduced with some American potatoes.

At Borsigwerk, in Silesia, the experiment has been successfully made of growing mushrooms in a coal-pit, at a depth of 126 metres below the surface of the earth. The fungi grow rapidly and plentifully in an average temperature of 8° Réaumur. The mushrooms so grown are said to be of finer flavor than those developed in the open air, and command higher prices.

The line of an interoceanic canal across the Isthmus of Darien, proposed by Ferdinand de Lesseps, starts from the Pacific coast, and ascends in the first place the Tuyra River as far as the island of Piriaque; thence a straight cutting, 16,200 metres long connects the Tuyra with the Chucanaque; the line then ascends the Chucanaque for 11,400 metres; then, turning to the northeast, it continues up the valley of the Tiati, to a point where a tunnel appears to be more economical than a very deep cutting. The tunnel passes to the south of the Peak of Gandi. On emerging, the canal continues through an open cutting for about ten kilometres to the deep waters of Port Gandi. The probable length of the tunnel is between thirteen and fourteen kilometres, and the cost of making the whole canal is estimated at 600,000,000 francs. This ship canal, if ever completed, will doubtless be the most stupendous engineering work in the world.

It will be a surprise to most readers to learn that Theodor Schwann, founder of the "cell-theory" in biology, is still not only living, but actually "in the traces." He is Professor of Physiology in the University of Liége, Belgium, and will soon complete the fortieth year of his professorial life. It is proposed to celebrate this noteworthy anniversary of the venerable professor by the presentation to him of an address, signed by prominent anatomists and biologists of all countries.

A company has been established in Paris for operating the system of pneumatic clocks successfully adopted in Vienna, an account of which was recently published in these pages.

Prof. Luvini, of Turin, has experimented upon the action of different gases, such as pure atmospheric air, oxygen, hydrogen, carbonic acid, chlorine, and sulphurous acid, on the eggs, or "grains" as they are called, of silkworms. Lots of eggs numbering one hundred each were kept in each of these gases for over two months, and then hatched. It was found that the silkworms produced from eggs that had been kept in carbonic acid showed more vivacity and vitality than any of the others. Those from eggs kept in hydrogen were the most backward in development. Those in oxygen became large and fat, but slow and lazy in their movements; after the fourth month especially, they would remain in one position for hours at a time. The eggs kept in pure air produced good sized silkworms, which, however, did not reach a large growth.

To ventilate a room without draft, make a hole through the wall to the outer air, in a corner of the room just above the skirting. Through the hole put one arm of a tube three inches in diameter, and bent at right angles. The arm of the tube reaching to the outer air should be in length equal to the thickness of the wall, and the other arm should be two feet long, standing vertically in the corner of the room; if desired, it can be covered with paper of the same pattern as that on the wall. A tube of the diameter given above is sufficient to ventilate a room of moderate size.

Near Nienburg, Hanover, waste pyrites from the manufacture of sulphuric acid having been employed for making roads and paths, it was soon found that grass and corn ceased to grow. Also, a farmer, on mixing well-water with warm milk, observed that the latter curdled. The explanation is, that the waste pyrites contained not only sulphide of iron and earthy constituents but also sulphide of zinc, and that by the influence of the oxygen of the atmosphere, and the presence of water, these sulphides were gradually converted into the corresponding sulphates, and the latter, continually extracted by the rain-water, soaked into the soil and contaminated the wells.

With a view to obtain, if possible, reliable data for the localization and diagnosis of cerebral disease, Dr. Lombard made a number of experiments designed to show, first, the normal relative temperature of different parts of the surface of the head; and, second, to show the effect of different mental states upon the different portions of the head previously examined. Mental activity, he finds, raises the temperature; the same effect is produced by simply awakening attention. The temperature is very rarely the same in all portions of the head when the brain is in the quiescent state.