Scientific and Useful.

Lake Wakatip Mail, Issue 1584, 8 April 1887, Page 3

Scientific and Useful.

FISH LIATHIB. A curious kind of leather, it is remarked by Qerber Zeitung, is actually known to some extent in Germany. It is fish leather, and is used for some of the fancy articles produced in Berlin and elsewhere The skin of the cat fish, it is said, affords an elegant leather for shoe straps, parses, &c. It is of clear, good colour, supple and tough enough to be useful

k FIBEPROOF TUBS. There is a curious tree, a species of Bhopola, of contorted appearance, and growing to a height of about twenty feet, which is said by Mr W.T. Thistle ton Dyer to be absolutely indestructible by fire, and which survives in South America where the dry pastures and bush are burnt twice a year, and everything in the way of vegetable life is destroyed with the exception of this tree. FBASL FISHING YACIIT. The steam yacht Chic i* being fitted up in Greenock harbour with a Brush-dynamo, for the purpose of pearl fishing in the Sovth Australian seas, and when the ocean bottom is thus examined by the electric lieht, there will no doubt be some woud« rful discoveries made. The steamer Hywna, belonging to the Liverpool Salvage Company, has also been fitted with tbe electrical apparatus for diving purposes. 10 COAT I BON WITH SILVBB. An ingenious process for giving a silver sur« face to iron has been devised in Austria. The iron is first covored with mercury, and silver is deposited upon its surface electrolvtically. The iron is then heated to about 300 deg. C., and the mercury evaporates, leaving the layer of silver on the surface of the iron.

WAVES. Dating a recent voyage of the U S. s, Juniata to South America, observations were made at to the height and length of ware*, with the following result, as reported by Commander Davis Height of wave from hollow to crest; 25 feet; length f*ora crest to crest, 375 feet; waro period, 7*5 seconds. The wind-Telocity at the time was 10 milrs per hour. The height of wave was me3Bnred by the elevation at which an observer could s. e over the crest when the ship wa» in the hollo*. The wave-period wa* estimated by counting the average number of waves per minute. The wave letigth was determined by the time occupied by the crest in passing a measured portion of the vessel's length. SCBMARIKB BOAT?. Submarine boats are a much older invention than is generally conceived ; but they are now coming prominently forward, because there is a useful field for their employment, and also because modern devices have rendered it possible to construct vessels which can be propelled safely beneath the surface of the water. Who first suggested the idea is not known ; but it seems well authenticated that in the reign of James I. a Dutchman named Drebbel designed a boat which was actually propelled by 12 oars under the surface of the Thames, the air being revived by some liquor, the composition of which Drebbel kept secret. The Marquis of Worcester, in his "Century of Inventions" (1663), refers to a similar invention, and there is a record that a man named Day sank with his submarine boat in Plymouth Sound in 177-4. It is, however, to Robert Fulton that we are indebted for the first definite ideas on the subject, for so long ago as 1801 he des<)ended to * depth of 25 ft. m the harbour of Brest, and demonstrated the fact that his" plunging boat" could be trueted to take himself and three companions under the water and retnrn to the surface in safety. This boat was named the Nautilus, and when beneath the surface was moved 500 yards in about seven minutes by two men turning the " engine," while Fulton regulated the position of the boat. On one occasion the boat remained beneath the surface for nearly sir hours. ARTIFICIAL >'OG. The latest invention is artificial fog! A patent has been taken out in Germany for an apparatus producing artificial fog, which surrounds plants and protects them from frost. The apparatus consists of a mercury-tube which, upon a fall in temperature and consequent displacement of its centro of gravity, puts into action a contrivance which ignites a vapour producing compound. An artificial fog is produced by this compound which, rising, is said to protect the plant against the inclemency of the weather.—lnvention. BRAINLESS FISHES. In some experiments performed some time ago by Mr. Vulpian, ia was found by him that a carp, when deprived of its two cerebri hemispheres, not only survived the operation, but continued to manifest cerebal faculties ; that after two or three days the fish began to eat; and that if small fragments of hardboiled egg I were thrown to it, it Went for them eagerly I and devoured them. One of these fishes having been accidentally killed at the end of six months, Mr. Vulpian found, as he states in a recent note to the Academy of Sciences, that no tendency toward a reproduotion of the extirpated organ was exhibited. METEOR SHOWEBS.

Prof. Richard A. Proctor maintains that most of the meteor streams with which the earth comes in contact are derive I from the earth itself—that is, thrown off by volcanic action at a time when the internal forces of our planet were sufficiently active to give the initial velocity, some twelve miles a second, requisite to carry them bejond the earth's attraction. Comet*, which ho regards as the parents of the meteor streams, he thinks may h%ve originated outside our solar system. Most of the comets whose orbits bolong to our system ho thinks originated in the larger planets. The sun is now, perhaps, giving birtli frequently to comets which probably pass beyond the limits of its attraction. SLAG PAVEMENTS, A new industry has been started in Middle* borough, the object of which is to uti isd blast furnace slag in a somewh it more definite and systematic manner than has hitherto boon attempted. The works where it is carried on belong to a limited company, the managing director ot which is Mr. J. A. Jones. One of the objects of the company is to make paving seta, fhese are produced by pouring blast furnace slag into metallic moulds, and then allowing the castings to cool slowly in an annealing furnace. Inasmuch aa these sets are as serviceable as those which are hewn from whinstone, and much more shapely, the manufacture and sale of them is of itself a good thing for Cleveland and for all purchasing district*. But there are further manufactures. It has been found if slag which has been annealed be pulverised and mixed with cement in proportions, and pressed into moulds and put aside for, say, three months, it seta into a peculiarly firm, bird, and solid mass. The value of these qualities was soon perceived, especially as applied to the manufacture of concrete flagstones. Consequently, the company referred to is making these and and laying them down for footpath*, railway 1 station platforms, and so forth. They are , exceedingly flat and smooth, and usually hard pa the iurfiqs,