SCIENCE SIFTINGS

New Zealand Tablet, 12 September 1918, Page 46

SCIENCE SIFTINGS

By "Volt."

Five Miles Deep. Everybody knows that the sea varies greatly in depth according to the locality, but not everyone realises to what an enormous extent. The greatest contrast is that between the English Channel, which has an average depth of under 200 ft, and the Pacific Ocean, which in parte attains the astonishing depth of over five miles. If it were possible to lift St. Paul's Cathedral bodily into the English. Channel the dome would still show above water. The Baltic Sea is also very shallow, and would barely cover the Westminster Clock Tower and the celebrated Eiffel Tower if they could be placed one on top of the other. Mount Everest, the highest mountain in the world, would be nearly covered in parts of the Pacific. Whippet Tanks. In a naval sense the usual "tanks," or landships, whether they be British, French, or German, have heretofore been of the battleship type—that is to say, they have been slow-moving, heavily armored, and powerfully armed craft, meant rather to stand up and fight to a finish than to dash in and out of a combat, and to depend on quickness of movement as the main weapon (says the Scientific American). But in breaking up and pursuing bands of infantrymen in the open there has been a distinct call for a "destroyer" type of tank—one that could travel at a comparatively high rate of speed and that possessed a higher order of mobility in general. To the British, the originators of the tank idea, has remained the further honor of developing a tank of the fast, destroyer type. This type, known as the "whippet," has already made its appearance on the battlefield in recent open fighting, and its debut has been crowned with success. The whippet has caterpillar treads of the usual design, arranged on either side of a sort of flat-car body. On the platform of the fiat car is mounted a single turret which houses the crew and the several machine guns with which the whippet is armed. The flat-car body measures 18ft in length, while the turret is 6ft in height, The engine is placed at the. rear of the gun turret, in a separate armored housing. During a recent engagement on the Western Front, near Cachy, the German infantry was seen assembling before the British positions. Seven whippets were ordered to disperse the Teutons, and in hardly no time they were upon the foe. Meanwhile the Germans, having the larger, slow-moving British tanks in mind, held their ground with the idea of playing machine-gun fire.and hurling grenades at the advancing foe. But soon the whippets were on top of them, opening a fierce machine-gun fire on the grey-clad groups, which soon broke and ran, pursued by the fast whippets. It is further reported that the whippets not only kept pace with the fleeing Germans, but in some instances overtook and crushed those who had escaped the machine-gun fire. It appears that the whippet tank can readily make 12 miles an hour, and a fully-equipped Teuton infantryman can hardly hope to maintain that speed for a prolonged period.