25 SEPTEMBER 1920, Page 19

PROBLEMS OF FLIGHT. *

Pasnars the most striking thing in Mr. Holt Thomas's interesting book on Aerial Transport, ie the folding map of the world at the end of it, which shows very plainly what increeae in the rapidity of travel could be made by an ideal aeroplane flying steadily at 100 miles an hour. Leaving London at 8 o'clock on Monday morning, the tourist or commercial traveller might be in Cairo on Tuesday, in New York or Calcutta on Wednesday, in Tokio, Cape Town, Buenos Ayres or Vancouver on Thursday, and in Sydney just after midnight on Friday. We have not reached that degree of perfection .yet, but Mr. Holt Thomas, who is largely responsible 'for the existing air-service between London and Paris, shows good reason to suppose that it may be attained within a very few years. It is little more than a decade since the first man flew across the Channel, in the face of danger and difficulties which have now practically been eliminated In the first 15 weeks of the London-Paris service which was inaugurated last year, the "aerial postmen " ancoessfully accomplished no less than 200 out of 227 flights on their programme, only 27 having to be abandoned on account of bad weather. On the very first flight the sole passenger, Mr. Stevenson-Reeoe, left Hounslow aerodrome at 9.10 a.m., had an hour for lunch in Paris, and landed again at Hounslow at 2.45 .p.m. The actual flying time on- a round trip of 500 miles was 4 hours 35 minutes, the average speed being well over the hundred miles an hour which is desiclerated for the -journeys already mentioned. A great part of Mr. Holt Thomas's very readable book isdevoted to the development of this London-Paris service, by which both mails and passengers arc now regularly carried. He then goes on to explain the elaborate organization which will be necessary 'before longer journeys can be accom- plished with the same certainty. The modern aeroplane and its engine are suited to stages of about 250 miles, and a trip of two or three hours is about as -long as the average .pilot would • (1) Aerial Transport. By G. Holt Thomas. London:TB:odder and Stcandeton• net.]—(2) Applied Aerodynamics. By -0. Y. ThatosOn, M.A. Sean publishers. VS 'la. acts

tare to undertake as a daily matter of business. Longer journeys can only be made on a commercial basis by a system of relays which will be costly to establish, though Mr. Holt Thomas has no doubt that sufficiently high fees can bo charged to ensure a reasonable working profit. He holds that the initial expenses should be met, at least in part, by subsidies from tho various Governments concerned. If the Governments of the world were to-day in the same financial position as they were before the war, it would be easier to agree in this view. Wo are glad to note the author's sensible remarks as to the risk of hastening the development of passenger services with large machines carrying a number of people. In the present state of aviation a forced landing with such a machine might be disastrous to the popularity of aerial passenger transport. " What is nothing more than an incident with the mail machine, a matter counted merely from the point of view of delay, may, with a bigger and more unwieldy machine, its cabin full of passengers, develop into something like a tragedy." Some admirable reproductions of air photographs, mostly of the London-Paris route, add greatly to the attractiveness of this needlessly bulky but interesting volume.

Mr. Thomson, who is a Fellow and Mathematical Lecturer of Corpus (Cambridge), and was formerly attached as a captain to the Royal Air Force, gives us an up-to-date treatise on Applied Aerodynamics' which is based largely on data collected by the Advisory Committee for Aeronautics during the war, and on the practical experience of the aeroplane factory with which he is connected. It is too technical for our criticism, but may be commended to serious students of aviation.