Page:Popular Science Monthly Volume 30.djvu/447

Rh that of mere chemical composition. Mr.F.L. Garrison has found the microscope a very useful test for determining the qualities of metals, through the revelations which it affords of the arrangement of their particles and their structure.

British Association's committee to observe the migration of birds has learned that birds on their arrival at the British Isles, as a rule, avoid high cliffs, and prefer to enter river-valleys, whence they spread gradually over the area embraced by the river's tributaries.

has determined by soundings the depth of the tubes of several geysers of the Rotorua district, New Zealand. In the case of the extinct geyser of Te Waro, he was let down the tube. At thirteen feet below the surface it opened into a chamber fifteen feet long, eight feet broad, and nine feet high, from one end of which another tube led downward to an undetermined depth. The author was satisfied, from his intercourse with the natives of the district, that by constant observations on the direction of the wind and the condition of the atmosphere, they had learned to prognosticate the movements in all these hot springs with wonderful accuracy. He had also observed during his residence that the geysers were in eruption only when the wind blew from a particular quarter,

proposed, in the British Association, a railway to connect the heart of Africa with London in ten days, as "a feat worthy of the age we live in." He would advocate the building of a railway from the two rivers Niger and Congo toward each other, and north and south at the rate of a mile a day, to form a spine through the continent. It would give the missionaries and traders two sides to work from, instead of one, as now.

are plants in the wrong place. They all probably have their right places and their uses somewhere in Nature's economy, though these are sometimes hard to appreciate. The most of them may serve to keep some desolate spot from being entiely bare, and the decay of their repeated generations furnishes mold to the ground, and may in time make it fit to bear something better. They all, too, have elements of beauty, and these will reveal themselves to every one who diligently searches for them. Many of them, if they were not weeds, would be prized as choice flowers, and some of them have been such.

on the vital statistics of one of the parishes of London, Dr. Meymott Tidy calls attention to the fact that the death-rate of England is decreasing, and that 150 people are added yearly to every 10,000 of the population. From this he prognosticates that at the present rate of increase the population of the country twenty generations hence will be 27,200,000,000, or enough, if distributed no more densely than the present population, to fill twenty earths. From 5,000,000 in the reign of Henry VIII, the population of England rose to about 7,500,000 in the early part of the reign of George III, and then, under the impulse of a long period of commercial prosperity, to 16,000,000 at the time of the repeal of the com laws. Now, 24,000,000 people are housed and fed in England and Wales, and depend on other countries for half of their food. Dr. Tidy regards the present increasing population and declining trade as serious facts.

mentions, as among the special applications which are made of the waters of the mineral springs of Continental Europe, the treatment of biliary obstructions and the plethoric forms of gout, at Carlsbad; of atonic gout, at Rogat; of calculous disorders, at Vichy and Contrexéville; of chronic articular rheumatism and gout, at Aix-les-Bains; of diabetes, at Neuenahr and Carlsbad; of obesity, at Marienbad; of gouty and catarrhal dyspepsia, at Hamburg and Kissingen; of anaemia, at Schwalbach and St. Moritz; of asthma, at Mont Dore; of throat affections, at Cauterets and Eaux-Bonnes; of scrofulous glandular affections, at Kreuznach; and of the great variety of chronic skin affections, at Aix-la-Chapelle, Cannstadt, La Bourbole, and Uriage.

, in the British Association, his optical studies in the essential oils, Dr. Gladstone, after explaining how the refractive equivalent of an organic compound may be used to determine its constitution, pointed out that the dispersive equivalents can be similarly used. He also discussed the refraction and dispersion equivalents of the turpenes, citrenes, camphor, and some other members of the group of essential oils, and showed how their values are of service in determining the constitution of those bodies.

has determined the salinity of the water from point to point in the Firth of Clyde and the Firth of Forth. The distribution of salinity in the Firth of Forth is constant all the year round, while periodical variations are observed through the whole mass of the water in the Firth of Clyde. It is evident that in the Forth River entrance, a mixture of river-and sea-water takes place by a true process of diffusion, and a constant gradient is maintained from river to sea. The dissolved matter of fresher water was found richer than sea-water in calcium carbonate.