NON-PUNCTURABLE TYRES.

Auckland Star, Volume XXXVIII, Issue 166, 13 July 1907, Page 10

NON-PUNCTURABLE TYRES.

Tests of the new tyres known as "elastes" indicate that a set will run at least 10,000 miles on a 24 horse-power automobile, and that they will reduce the expense for tyres fully one-half. They are made by filling the ordinary covers of pneumatic tyres with a heat-mixed composition of glue, glycerine and chromic salts. The material solidifies in a few days into a soft rubber, forming a cushion for all roads, and having entire immunity from puncture. POPULATION DENSITIES. Egypt proper is the most densely-popu-lated country, having 750.5 per square mile. Belgiuh comes next with 588, then Holland. The United Kingdom has 341.6, Japan 296.4, after which come the other European countries down to Russia with. 51 and Sweden with 29. The United States has only 21.4, and the South American Republics all less, Venezuela having only 3.4 persons per square mile. In England there is an average of just about one person per acre. QUADRUPEDS THAT LAY EGGS. The salesman, as lie wrapped up the eggs, conversed politely. "There are quadrupeds that lay, ma'am," he said. "That lay eggs?" "Yes. They are mammals, ma'am, too. Their home is in South America, their Dames are the ornithorhynehus, or duck-billed platypus; and the echidna, or porcupine ant-eater. They are the lowest mammals known." "Really." "Oh. yes. The duck-billed platypus lays two eggs at a time. But the. echidna lays but one egg, which it carries in, a natural pouch beneath its stomach — there's an idea for the hen there—until the kid echidna, so to speak, is hatched out." CURIOUS CAVE DWELLERS IN" SAHARA DESERT. A discovery of curious interest has been made by Mr Hans Vischer, the English resident at Kuka on Lake Chad, Vjri Northern Nigeria, Africa, in the course of a hazardous exploration he is making in the Sahara desert. In the country around the Gharian mountains a colony of cave dwellers was found. The strange inhabitants of these subterranean residences excavate a huge, deep hole in the ground, which forms a kind of quadrangle or courtyard, reached by means of narrow entrances about thirty feet in length by three feet broad. All the rooms and other apartments of the occupiers open upon this courtyard, and are excavated out of the solid earth upon all sides, the internal lighting of the apartments being gained from the aperture opening upon the quadrangle. The rooms themselves are very dark. A remarkable feature of this strange . community is the absolute cleanliness that prevails everywhere. UTTLISrNG A VOLCANO. The unusual and daring proposition is now made to make at least one active volcano perform constructive work of positive commercial value. The idea seems to have been adapted from the familiar one of drawing molten iron from a furnace and conducting it along the earthern floor through shallow open trenches into moulded spaces, where it cools and becomes the pig iron of trade. Hilo is the important seaport on the east coast of the Island of Hawaii, in the Sandwich Islands group. Its harbour facilities are insufficient to meet the demands of present day commerce, and in order to provide suitable shelter, great breakwaters must be constructed at large ; cost. The idea is to construct a big trench from Mount Kilaueau to the shore and then tunnel into the pit of one of the craters and release the molten lava, just as a furnaceman opens acupola when making pig iron. One difference will be that where the founder uses a long iron rod to poke a hole, the volcano is to be opened by letting off a big charge of high explosives. Notwithstanding the somewhat startling nature of the story, it is stated that '"engineers who have been considering the scheme are strongly inclined to the opinion that it is not impractiable. EFFECT OF THE MOON'S SEPARATION FROM THE EARTH. If the moon had never been born, Professor W. H. Pickering points out, the highest intelligence on earth would not have advanced beyond that of the present deep-sea fishes. As the original earth nebula condensed, the lighter materials were distributed quite uniformly over the entire surface, but these are now missing from one hemisphere, the reason seeming to be that a portion of the earth's crust has been thrown off by tidal action, forming the moon. The moon, it is computed, equals a mass having the surface area of our oceans and a depth of 36 miles; and it is concluded that the crust of the earth, when 36 miles thick, must have been torn away, over three-fourths of the remainder breaking apart to form the eastern and western continents, with Australia and other islands. This great rupture gave the earth's surface its chief irregularities, with a mean difference of three miles between the levels of the continental plateaus and the ocean beds, and as the water condensed in the cooling depressions, with the Pacific where most of the moon had been, tlie dry land was formed that has made human life possible. We may consider that without this, change the earth would be now in the condition of Venus, with water over its whole surface.