ATTACK FROM THE AIR

Waikato Times, Volume 125, Issue 20991, 19 December 1939, Page 2

ATTACK FROM THE AIR

VARIOUS TYPES OF BOMBS PRECAUTIONS IN ENGLAND England’s air-raid precautions were the subject of an address by Mr r. M. Corkill at the Invercargill Rotary Club. Gas was by no means the weapon to be feared as much as high explosive, Mr Corkill said. It was commonly thought that aeroplanes would fly over and demolish towns in a force, but that was quite wrong as the cost of such operations would be prohibitive. Enemy efforts would be concentrated on military objectives and concentrations of troops. In London itself there were very few factories of national importance and an attack on London would have little military value. The only value of a raid on open towns would be its moral effect, and that was often the opposite of what was intended. When Madrid was bombed, for instance, the effect was to strengthen the resistance of the people. Three Different Ways Bombing aeroplanes bombed in three different ways—high altitude precision bombing, in which the conditions must be favourable, medium height bombing at 5000 or 6000 feet, generally ending in a dive, and “chimney-hopping” or “hedge-hop-ping.” Machines that went in for “chimney-hopping” were too close to within range of pnli-aircraft fire, but they were travelling so fact in relation to the ground that it was practically impossible to hit a tar get with a bomb. Difficulties of sighting in view of the high speed at which the bombers travelled, the effect of anti-aircralt fire, and weather were among the factors that militated against successful bombing.

Explosive bombs, Mr Corkill said, varied according to their objectives —heavy, medium, and light bombs, wkh instantaneous or delayed action fuses. Some had armour piercing noses and others were semi-armour piercing. Other types were incendiary and gas bombs. They also had to defend against gas spray. Provision for protection against direct hits by heavy bombs was an utter impossibility. It had been shown that for protection against the 5001 b or general purpose bomb a covering of 50 to 70 feet of earth or 15 feet of reinforced concrete would be required, and that was not practicable. They could only expect to protect themselves from splinters or from the effects of a bomb when it was not a direct hit. Danger of Suction When a bomb fell in a street and exploded near a building fragments were thrown in all directions. Then the wall of the building was driven in by the “blast,” and immediately after it was pulled back by the suction, which was far more deadly, because buildings were made to etard wind and other pressure from outside, but not from inside. The result was the demolition of the building. The general aim was to provide protection for a building at 50 feet, from the point of impact of the bomb. A nomb released from an aeroplane did not drop vertically at once, but followed the course of the aeroplane for a while and then fell to earth in a parabola, like a thrown stone or water from a hose. Even at 2000 feet, therefore, a bomb would land at an angle, and could also strike the wall of a building and penetrate it before exploding. It was thus necessary to give the walis as much protection as the roof. A bomb falling from a great height had been known to plough its way at an angle to a point below a dugcut and explode from there, wreaking untold havoc. Incendiary and Gas Bombs Mr Corkill described some of the incendiary bombs that were used oy aeroplanes. The ordinary small incendiary bomb, he said, weighed about 21b 3oz and was 12 inches bv two in dimensions, so that an aeroplane could carry as many as 2000 or 3000 of them. They burned for two or three minutes, and it was impossible to extinguish them with water .which caused the thermite to explode. The method of treatment was to smother them with fine sand, ■and put them into a bucket of sand with a shovel, the handle of whicn was about 10 feet long. In Spain they were not greatly used, and only two per cent hit their objective Some of these bombs threw out •pups” and caused subsidiary fires

Gas bombs, Mr Corkill said, were not generally destructive, but were demoralising. He described th® masks that were issued to the civilian population in England, and said that every one of the British masks was entirely effective against every known gas. There was, he said, a popular rhyme: I have a little gas mask Which costs me lots of tears Because I cannot get accustomed To breathing through my ears