The field covered by the title of this paper is a very comprehensive one, and is too large to be dealt with in a single lecture. Only certain aspects of the subject, therefore, will be dealt with, and very brief reference made to such tests as have been described in other papers.

The subject naturally falls into three divisions:—Ground tests, tests on the water, and aerial tests, and it will be convenient to deal with them in this order. The methods of test described are those in use at the Marine Aircraft Experimental Establishment, Felixstowe, the official seaplane testing station, and, as far as is known, these methods are as up to date as those in use in other countries.

If it is felt that gaps exist on which information is desired, the inquirer is referred to Squadron Leader England's lecture on “ The Practical Side of Performance Testing of Aircraft,” which was published in the Aeronautical Society's Journal of January 1928, and to other papers which are mentioned.