Science Sittings

New Zealand Tablet, Volume XXXV, Issue 2, 10 January 1907, Page 35

Science Sittings

By 'Volt'

Speed of Trains and B rds.

A German statistician has been drawing up comparative tables of the speeii of trains and birds. A train which travels at the rate ;of CU miles an hour covers 28 yards in a second, and this is exactly the- pace at which a. gazelie can gallop. Racehorses gallop at the rate of 25 yards a second; and an ostrich, -when it makes use of its wings, can do 36 yards,, a homing pigeon 55 yards, larks 18 yards, :and swallows as much as 150 yards. This is very nearly three times as fast as an express train, -and no one who has seen the ease with which ordinary 'birds keep up with and dart past a fast train will doubt these calculations.*

Destructive Shell-Fish.

In the tropics rock-boring and wood-boring shellfish are among the greatest natural agents of destruction in the shallow waters of the sea.- -It was not until the builders of iron ships launched the present navies of peace or war' upon the deep that the hulls - of vessels • moored for any time in harbor were safe from their attacks. The shelis of these molluscs are elegant and beautiful. They are often, not at all obviously adapted for boring. Frequently they are very thin, looking almost like hardened paper. Yet they bore through teak or oak,^ hardened clay, chalk, rock and ~ concrete break-waters.

The Ships That Sink.

What becomes of the ship that sinks in mid-ocean ? If it is of wood it takes,, in the first place, considerable time for it to reach the bottom. In a hundred or more fathoms of water a quarter of an hour will elapse before the ship reaches bottom. It sinks slowly and when the bottom is reached it falls gently into the soft, oozy bed, with no crash or breaking ' ' • Of course, if it »is laden with pig iron or corresponding substances, or if it is an iron ship, it sinks rapidly and sometimes strikes the bottom with such force as to smash it to pieces. Once sunken a ship becomes the prey of the countless' inhabitants of the ocean. They swarm ovet and through the great boat and make it their home, besides this, they cover every inch of the boat with a shick layer of- lime fins takes time, of course, ' and when one generation dies another continues the work, unttl finally the ship is so laden with heavy incrustation^,, corals, sponges, and barnacles that, if -wood, the creaking timbers fal ar^lea ßl^^' ""^ "" abS ° rbed * the waste

Iron vessels are demolished more quickly than those »t?°\ hl( * *fr fojf. centuries. The \ onh « metals that withstand the .chemical action' of the waves are gold and platinum, and glass .also seems u^affec«2L H m^ Ite1 ter Ihow1 how gold may be hidden in the ?S? 'f ,i , - aIW^ yS te gold when recovered, and 1 this fact? explains the many romantic and adventurous ' wrSf hi d den submadlie measures lost in sM p -

Canadian Forestry. TTmW,.i he ?? ini ° n ~ of } he Dominion Superintendent of * ?£nr ? Y h Ca ™d a rj undoubtedly holds the .first place 3 Itt-^w n^ bei "^" Oduclng countries of the world, and notwithstanding -the great drain now put upon its resources in this respect by the demamds of fore gn countries, he thinks -that its lead may be increased by 3 whlS° U rV ma^ agement ° f its K^at forests The vi^to white pipe, he says, cannot last many years longer but in the Douglas fir, the, cedar, the western white pine the spruce, and the hemlock Canada possesses all « but inexhaustible treasures. The spruee * is the most S2 eI LJSS bb t ted ti, V^ i - U fi S SPCCieS 0?^ extend. SSS tn 4^A^ p g$ aßaaa B aa 11 -