Page:Popular Science Monthly Volume 2.djvu/530

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plummet, has reached the required depth, an electric current is sent from the battery on shipboard to the coils below; the magnetism thus generated opens the valves, and the vessel is filled and ready to be drawn up.

In his evidence before the Royal Commission on the water-supply of London, Dr. Parkes states that where the population of any town shows a considerable amount of diarrhœa, and also of typhoid fever, it would lead him to regard the water-supply with suspicion; for the health of the population, as regards these diseases of the intestines, seems to be very much influenced by the purity or impurity of the water consumed.

It is proposed to employ tin-foil in place of paper for decorating walls. The foil for this purpose is cut in sheets about 16 feet long and 40 inches wide. After having been painted and dried at a high temperature, the sheets receive the ornamental figures, and are then varnished and again dried. The hanging is done much like paper-hanging, varnish being applied to the wall instead of paste. The foil excludes damp, and can be laid as readily on an irregular as on an even surface, and thus the highest artistic effects can be produced at pleasure.

A writer in Hardwicke's Science Gossip tells of a water-wagtail which he saw acting as purveyor to a young cuckoo. The wagtail was seen, again and again, to fly down from a tree, and run along the rail on which the cuckoo was perched, bringing each time to the latter some insect to supply its hunger.

Orange Cultivation in Louisiana.—There is a steady increase, in the orange district of Louisiana, of this species of husbandry. In Plaquemine Parish some 2,000 acres are occupied by orange-groves. Usually, there are one hundred trees to the acre, and a healthy tree will bear from 500 to 2,000 oranges, 1,000 being a fair average field. They bring, on an average, $10 per thousand.

The iron mountains of Missouri, according to Prof. Waterhouse, contain enough ore above the surface, to afford, for 200 years, an annual supply of 1,000,000 tons. Shepherd Mountain is 600 feet high, and its ore contains a large percentage of iron. Pilot Knob rises 1,114 feet above the Mississippi; its base, 581 feet from the summit, is 300 acres, and the upper section of 141 feet is judged to contain 14,000,000 tons of ore. Iron Mountain has an elevation of 228 feet, and an area of 500 acres at its base. The solid contents of the cone are 230,000,000 tons. At the depth of 150 feet, the artesian auger was still penetrating solid ore. The iron from all these mountains is strong, tough, and fibrous.

Died, October 28th, aged sixty-five, Dr. Friedrich Welwitsche, the distinguished African botanist. He got his first lesson in his favorite science from a village apothecary, and so an interest was awakened for botanical studies. The "Flora of Tropical Africa" has received from him very important contributions. He acquired distinguished reputation also as an entomologist and zoologist.

In criticising the evidence given by Dr. Letheby before the Royal Commission on the London water-supply, Dr. Hassel, in "Food, Water, and Air," maintains that "it is a fact, notwithstanding Dr. Letheby's evidence, well-established and generally accepted, that cholera is communicable by water, and has, over and over again, been disseminated by the water contaminated by cholera-discharges. It is also a fact that on more than one occasion that dreadful disease has been communicated by Thames-water."

A recent issue of French coin, made from Australian gold, has been found so brittle as to break easily under ordinary use; it has accordingly been recalled. The brittleness is supposed to be due to the presence of a small percentage of antimony and arsenic, both extremely difficult to remove. These substances are said to produce a like effect in all metals or alloys which are subjected to the molecular changes induced by the pressure and heat developed under the action of the dies in the copying-press.

The archives of the Paris Jardin des Plantes contain 6,000 volumes and over 1,500 manuscripts that have hitherto been huddled away as so much lumber. Recently M. Milne-Edwards has arranged for examining, cataloguing, and placing at the disposition of the scientific world this valuable collection. There are several MS. by Buffon, Cuvier, and Daubenton, and a series of pen-and-ink drawings by the last-named naturalist, representing the various types of merinoes; also many albums filled with drawings of plants and flowers.

Dr. Günther shows that the whitebait, a fish highly esteemed by epicures, is nothing but the fry or young of the herring, and this he proves by showing that both fish have the same number of vertebrae and of lateral scales, as also the same arrangement of fins and teeth. This statement is further confirmed by the fact that an adult whitebait in roe has never been found.