MODERN SCIENCE.

New Zealand Herald, Volume LXI, Issue 18897, 20 December 1924, Page 27 (Supplement)

MODERN SCIENCE.

ITEMS OF INTEREST. ERUPTION OF GEYSERS. REASONS FOR PHENOMENA. Geysers have often been'compared to volcanoes, presenting in miniature with water instead of molten rock, all the phenomena of a volcanic eruption. lhe fecource of the heat is the still hot lavas below the earth's surface and is connected with the past volcanic energies of the thermal region. The accepted theory of these natural steam engines, which heats the. name of the illustrious Bunsen depends upon the well-known fact that the boiling point of water rises with the" pressure, Kd is, therefore, higher at the bottom of the tube than at the surface. In the long and narrow or irregular cevser tubes the ebullition in the lower part of the tubes is only possible at a Much higher temperature than causes water to boil at the surface due to the. eight of the water column above it. The heat from the hot lavas continuously applied to water at the bottom of the uevser tube causes it to be heated to a high temperature, while the water near (ho surface is still coolEventually the water at the bottom reaches the pressure boiling point, when frteam is formed, lifting the water above it, and causing an overflow at the top. This overflow relieves the pressure, and al that part of the column, whose temperature was previously below the boiling point, but now exceeds it, flies into steam and ejects the water above with great Violence. . , ' The water that is erupted flows back Into the tube or percolates through the porous lava and is reheated for the ensuing eruption, whose period depends upon the intensity of heat. Some small geysers erupt, every few minutes, while the inter- ■ vai between eruptions of some of the larger geysers is measured in days and even weeks. * BRICKS OF LIME-SAWDUST. Building blacks of lime and sawdust, to which sand, ashes, or other materials may be added, have been a subject of late research, The product can be made in Sheets for roofs or inside walls, and is, claimed to have such advantages as resistance to intense heat and to moisture, us well as being an efficient insulator against sound. The sheets or blocks may be readily sawn, though hardening after k few days. SOURCE OF FLOATING ISLANDS. Floating islands, long known in rivers, Jakes and the cpen sea, have been found by Harufusa-Nakano, a Japanese investigator, to have various origins. Such islands exist in the inland waters of Japan —some being evidently fragments broken from a plant-covered shore by ice end changing water level, while others are clumps of vegetation that have started in shallow lakes and lost their root anchorage. TREES ACTING AS AERIALS. Forest rangers in the large reserve in the State of Washington have succeeded in making trees talk. Two of them, tired of carrying wire, experimented, and found that they could make the branches of firs and hemlocks act as aerials. They drove, a copper nail into the base of the trunk and, connecting it to the radio fender, started every twig and leaf sending wireless waves. Messages have been received two or three guiles away by this method. Mors experiments are being conducted in the woods to increase the efficiency of the method, so that any station can be informed of any occurrence by wireless instead of telephone. ARTIFICIAL SUN BATHS. 'Aftificir.l sunlight is to be provided for monkeys in a new building at the London Zoological .Gardensto be- switched on when the sun fails, an experimental scheme being in hand for testing the health benefits of this device. It will be* an adaptation of methods which are, being employed in furtherance of human health. In the new house at the Zoo the substituted light can be brought into use when London fog shuts out the pun 'or its ultra-violet rays are otherwise obscured. Alike in the open under a verandah roof and in an inner chamber clusters of powerful electric lights will serve at such times. A new kind of glass transparent to the healing.rays is to be used for windows. MYSTERY OF THE MOON. By chemical analysis of lavas of the Hawaiian volcanoes, Dr. Henry S. Washington, famous expert on the chemistry of the earth's crust, hopes to find some clue to the mysteries that lie beneath the Pacific Ocean. For example, there is a theory that the' moon was once part of the earth, and was pulled out of it millions of years ago, leaving a hole that became the bed of the' Pacific. Another theory is that the'continents really float oh a semi-liquid layer, and that they slowly drift about, ho that the earth's appearance a million years from now will be vastly different from the earth as we know it to-day. The lava, it is believed, holds the clue to these mysteries. THE MAGNETIC SPELL. When ships pass on their way to and from Liverpool, and come to a particular fcpot in the Mersey, their compasses become agitated in a wholly improper way. Home magnetic spell is laid on" them, and the only explanation that has suggested itself is that the iron parts of some ship wrecked there. have become magnetised by some shift in the wreck's position joined to the action of waves or currents, ■there are a number of places in the world where something magnetic on the coast or on the sea bottom affects a ship's compasses. Magnetic Island, off TownsvUe, on the coast of Queensland, was so called because it appeared to upset the compass of Captain Cook's ship. In the out of St. Lawrence there arc similar disturbances. EARS THAT TELL AGE. ♦ P n to , the P resenfc if has been impossible to tell the age. of a fish with anv degree of accuracy. But now Professor W. J K Harkness of the University of Toronto declares that by looking into the fish's ear one can tell its age. This scientific conclusion will prove of value to fish canneries and fishing preserve experts. In he internal ear of the fish there is a bony pocket. In this pocket there is a tiny stone, called an "otolith," which rolls about as the fish tips this way and that, and helps it to know if it is* right «id« up „ As the fish frows elder the I otolith grows larger. Professor Hark- j ?, e " "as , made a study of the rate of the Otolith s " growth and can now tell ! from the size, of this " earstono " just how old the fish really is. | CARRIER PIGEONS AND RADIO. A Spanish experimenter, chief of the ■ radip station at Paterna, near Valencia, re- j ports some curious observations he has made of the apparent effect of radio on the sense of direction of carrier pigeons. Dur- | log a. transmission he released several of : ™» Pigeons, which circled over the station. I Aach time that they passed directly over | !i ,c aerial they were observed to falter in I their flight, and until they had more or I iT .£& er<)d " through this part of too air showed absolutely no recognition "i the location of their house. As soon as *ney J l3 /* passed over the aerial they returned then-flight directly to the pigeon.it *l Inis manifestation took place, iwtes i the experimenter, no matter what iS gt .u used, but under 100 watts Jadiation l - he effect was less noticeable WW the pigeons could quickly find their !*»J through the charged area. |