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APPENDIX **.

Minute by the Prime Minister dated 28th May, 1940.

This day should be set up a Committee to review again the whole question of smoke screens to hide our factories from bombing attacks. The .D. R. Committee examined this question two years ago, and dropped it for reasons which did not at the time seem convincing to me. If a large area is made misty and obscure at night, the factories in it cannot be identified, and pure chance will regulate hits. If several other areas which do not contain factories are equally made misty, the enemy may be diverted, and confused. Let all information in this subject be examined, and proposals for action made, including the burning of briquettes in cottage fires. Is it true that at the present time the factories are actually obeying the peace-time regulation of limiting their smoke?

The report should be made to me as Minister of Defence within three days.

APPENDIX B.

PROGRESS OF OPERATIONS UP TO THE END OF DECEMBER, 1940.

(1) Oil burning generator schemes.

The oil burning apparatus in use has been developed by Engineer Rear Admiral S.R. Dight, C.B.E. The small generator emits a light grey smoke, can be operated for five hours and consumes pool diesel oil at the rate of 2 gallons an hour. The large (Haslar) generator produces 50 times as much smoke, which is somewhat darker in colour, for 8-10 hours with one refuelling; it consumes boiler fuel oil and water at the rate of 100 gallons of oil and 75 gallons of water per hour.

In operating a smoke protection scheme a ring of small generators is placed round the "target". The generators to windward are operated and a smoke haze, having the appearance of a natural ground mist or fog, develops over and around the target. Where Haslars are used they are stationed on or within the small generator circuit to produce an increased density of smoke. The scheme is designed to operate under conditions of bright moonlight in winds up to 10 miles per hour.

Vital targets. Lists of industrial establishments for which smoke protection was desired were obtained from the Admiralty, Ministry of Supply and Ministry of Aircraft Production, who had met to co-ordinate their requirements and to arrange mutual priority for the purpose of smoke protection.

Summary of Operations. Commencing with the July moonlight period smoke protection schemes have been operated over vital targets every month, with the exception of August, up to and including December. The progress of smoke operations has been kept under close review by the Chiefs of Staff Committee for the first few months at the end of each month's operational period - and it will be convenient to set our briefly below what has been done each month, referring to the Committee's conclusions where appropriate.

Bang

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