Science Sittings

New Zealand Tablet, 23 July 1908, Page 35

Science Sittings

BY 'VOLT Starboard and Port. Why do the sailors call the right hand side of the ship ' starboard ' and the lift hand ' port ' ? For the answer it is necessary to go back to the days of the Norsemen and Saxons. In the viking ships the warriors hung the ' bords,' or shields, on. the side of the ship above the places for their oars. The viking himself held^ the steer oar, which was fastened to the right hand side of the stern. Thus, the right hand side of the ship became known as the steer side, and as the bords of the warriors were hung there it was called the ' sterbord,' or starboard side, while the lower, or lurking, side became the larboard. Bord eventually became corrupted into port. Earthquakes. A scientist who has made a special study of earthquakes says : — ' Let us imagine the influx of the sea into one of the fissures formed in the earth's crust. On coming into contact with molten matter it would instantly be changed into gaseous steam, expanding to more than 18,000 times its original bulk. This would press with enormous force upward upon the crust of the earth and downward upon the surface of the liquid lava. If there were then no vent for the lava to escape an earthquake would result.' There are other ingenious theories which have weight, such as that of Davy, who when he discovered the metallic bases of the earths and alkalis, conceived that water may penetrate to these metals if they exist underground in an unoxidised state, and so set free sufficient gaseous matter to cause an earthquake. Shrinkage of the earth's crust is also to be taken into account. Concerning the Ocean. The oceans occupy three-fourths of the surface of the earth. A mile down the sea, the water has a pressure of a ton to every square inch. If a box 6ft deep was filled with sea water, which was then allowed to evaporate, there would be 2111 of salt left in the bottom of the box. Taking the depth of the ocean to be three miles, there would be a layer of salt 440 ft thick covering the bottom, in case all the water should evaporate. In many places, especially in the Far North, the water freezes from the bottom upward. „ Waves are deceptive things. To look at them, one would gather the impression that the whole water travelled. This, however, is not so. The water sta\s in the same place, but the motion goes on. In great storms waves are sometimes 40ft high, and their crests travel 50 miles an hour. The base of a wave (the distance from valley to valley) is usually considered as being 15 times the height of the wave. Therefore a wave 25ft high would have a base extending 375 ft. The force of waves breaking on the shore 13 17 tons to the square -foot. A Curious Tree. The Welwitschia mirabilis is a wonder of the vegetable kingdom. It grows on the barren land of the western side of Africa, where rain is almost unknown, and the only moisture is that from dews which fall at night. This plant was discovered in iB6O by Dr. Welwitsch, an eminent scientific traveller. The welwitschia is a tree which lives for many years, many specimens being estimated as more than 100 years old. Every year of its life increases its size, yet it never grows higher. Rising just above the ground, this strange plant, looking like a rough round-table, regularly enlarges by adding concentric layers to its circumference. The flat upper surface of the trunk is very hard and .dark, resembling in color and texture the crust of an overbaked loaf. The trunk attains .the size of from fourteen to eighteen feet in circumference, but is never more than a few inches above the ground. The welwitschia is remarkable in the fact that it never loses its first two leaves and never gets any more. These leaves increase in size year after year until they attain the length of six or eight feet or more. They are flat" and leathery, and frequently split into numerous straps.