Some clarification of ideas in the fog of argument about shelters is to be gained from a study of the Government's own recommendations. It has published a number of hand-books on air-raid precautions, one of which, N 3 deals with the design end construc bomb-resisting shelters, writes the scien! correspondent of the "Manchester Guardian." It will be noted that the title has been carefully chosen, for "bomb-resisting" has not quite the same meaning as "bomb-proof." But the designs in Handbook 5 A include those of shelters which are considered to give adequate protection against a direct hit by a 500b. bomb travelling at maximum speed—that is, about 1°00 feet per second after falling from an aeroplane at 15,000 feet. In popular language such a shelter would be described as "bomb-proof." because it would keep out all ordinary bombs, fcr number of bombs of more thab 5001b. weight that are dropped is relatively small and the chance of being hit by one is extremely smal! Certainly the majority of persons would feel virtually safe in such a shelter.
What, then, does Handbook 5 A recommend? It gives designs for circular and rectangular shelters for 200 persons and a rectangular shelter for 1,200 persons.
Tt is stated that the roofs of shelters should consist of concrete five feet thick. ternally reinforced with keep out 300b. bombs w metal cases and still heavy cases, To keep out 500b. bom metal cases reinforced-conerete roof: feet six inches thick are required. Bu foot will be generally adequate. The rector gular shelter for 209 po: ts essentially of a single block of reinforced concrete, with hollows inside for accommodating people.
Text read from the printed page and cleaned; old type leaves the occasional error.