Page:Popular Science Monthly Volume 9.djvu/536

512 will publish in the fall two volumes by Prof. Wyville Thomson, on the "Results of the Challenger Expedition." This work will be illustrated by drawings, made on the spot by Mr. Wild, the artist of the expedition, of the many curious and beautiful creatures now for the first time brought to light.

grape-fungus, which first appears on the leaves of the grape-vine, in the form of a minute yellow spot, was described by Dr. Engelmann, at a recent meeting of the St. Louis Academy of Science. It makes its appearance just before and during the flowering period, as far as known attacking only the leaves, or rarely the petioles and peduncles. It kills the leaves, and thus cripples the plant, and attacks all varieties indiscriminately.

of wheels was lately taken from beneath the baggage-car of the California and Oregon express train at Sacramento, which had traveled in daily use 91,800 miles, nor were they worn out even then, but had become loose on the axle.

Challenger Expedition returned to England May 23d, after an absence of three years and five months. During that time the vessel sailed 61,840 miles. The number of soundings made was 370, of dredgings, 360. Some hundreds of specimens were sent home during the voyage. The mortality was not above the mean, and, when it is remembered that the average time at sea was 220 days per year, it is surprising that the health of those on board (259 in number) was as good as it was.

the thirty years, 1841−'70, the death-rate of England and Wales was nearly stationary, about twenty-two per thousand. It must not be supposed, however, that in the mean time no progress was made in sanitary science. The rapid development of manufactures led to the crowding of people in towns, and this must have tended to produce a higher death-rate. The local statistics strikingly exhibit the influence of this massing of people in manufacturing and mining centres. For instance, while Cambridgeshire shows a progressive decline of death-rate, in the West Riding of Yorkshire, where the urban population has been enormously increased, the death-rate has been steadily rising.

of pig-iron is soon to be tried in Paris. In constructing a roadway of this kind, a bed of mortar is first laid down, which is covered by a strong layer of asphalt; it is in this layer that the iron cakes, which are about 1.6 inch thick, are set. These cakes, it appears, preserve the homogeneity of the bitumen and prevent its depression, and render the asphalt less slippery for horses. This pavement will cost more than the compressed asphalt, but it is estimated that it will save 50 per cent. of the repairing expenses, which are very considerable. The end desired is to avoid, by the adoption of this kind of pavement, the depressions in roads over which a great deal of traffic passes. To attain this, it does not suffice to pour bitumen upon a well-prepared ground lightly covered with a coat of lime; the resistance of the ground should equal that of an old macadamized bank; and a very thick bed of mortar, which should be very homogeneous, should be laid before the asphalt.

process of gas-manufacture has been patented by Malam, manager of the Dumfries (Scotland) Gas-Works. The advantage claimed by the inventor for the new process is, that a large proportion of the liquid hydrocarbons, which would otherwise go to form tar, are converted into gas, and thus an increased production of gas is insured to the amount of 3,000 or 4,000 feet per ton, while the quality is not deteriorated.

announcing the sale of the Hoosac Tunnel machinery, the Engineering and Mining Journal remarks: "The contractors completed, in the most satisfactory manner and it is said at a considerable pecuniary sacrifice, a most difficult work (the tunnel), and one which is of considerable advantage to the State (Massachusetts), and it is greatly to be regretted that the government of a great State should resort to those devices, to avoid the fair and honest performance of their engagements, which, when practised by individuals, are characterized as 'tricky' and 'dishonorable.'"

which has been kept for some time in the state of ebullition does not make so good an infusion of tea as water "just upon the boil." A reason for this is suggested by a writer in the Chemical News, who says that the escape of dissolved gases might possibly account for the inferiority of tea-infusion made with long-boiled water. To test this, he passed for ten minutes through boiling water a stream of carbonic-acid gas, and then made an infusion of tea with it. The result was decidedly better than when water was employed that had boiled for the same length of time without the addition of the CO2.

depth of the Pacific Ocean between Hawaii and Tahiti, as developed by the soundings of the Challenger Expedition, ranges from 2,000 to 3,000 fathoms, with one exception of 1,525 fathoms. The bottom, except near the islands, is mainly red clay, with much oxide of manganese in small concretions and many foraminifers.