IN introducing the Lecturer, Colonel Moore-Brabazon said that Mr von Baumhauerwas a distinguished aeronautical engineer and scientist in his own country, andthat the Institution felt very grateful to him for coming over for the specialpurpose of giving aeronautical people in England some information regarding hiswork and its results The Chairman then called upon Mr von Baumhauer to deliverhis paper

Mr A G VON BAUMHAUER We want progress in aviation because we are convinced thatefficient air traffic will give interesting and useful new possibilities

Wind channel tests have shown that wings can be made with a lift-drag ratio offar more than 20, and that streamline-bodies may have a resistance which at highspeed is so small for a body of the cross section of modern transport machinesthat the lift drag ratio of the whole could still be over 20(eg, at a speed of 160 m p h ) So it would seem quitesimple to build efficient aeroplanes

But it is not really so simple

IN approaching any problem in Aerodynamics the student, and the severely practical engineer, whose academic knowledge may be limited, are too frequently confronted with two difficulties The first of these is that though the literature on the subject is extensive, yet the information sought usually has to be collected from a number of sources and the second is that when found the information is frequently presented in such a manner as to be of little immediate practical value without a certain amount of simplification

The object of this paper is to collate and present in an immediately useful form the information contained in parts of the following publications

THE use of a camera in the air dates back many years, and some attempts wereactually made as early as 1858, when Mons Nadar successfully took photographs ofParis from a balloon From these initial attempts the taking of air photographshas always made an appeal to the Services both from a Military point of view andfrom the map making aspect

The development of air photography in the British Air Service dates from theformation of the Royal Flying Corps in 1912 Very little progress was made untilthe outbreak of war in August, 1914 At this time the British Air Service wasequipped with a few press type cameras and some simple portable developingequipment From these small beginnings, however, grew the Photographicorganisation of the Royal Air Force which towards the end of the War wasproducing thousands of negatives and prints every day The equipment in use wasnecessarily designed under War conditions, and the personnel handling thisequipment had often to forsake the camera for the machine-gun Thus as a naturalconsequence the equipment, excellent though it was, had not all the refinementand accuracy which is desirable or demanded for survey purposes