The automotive engineers have had a most important part in the conduct of the Government aircraft programme. It is well known that the development of the Liberty Engine is properly credited to engineers who are members of the Society of Automative Engineers and whose work has been greatly facilitated by the present and past activities of the society. Due credit must of course be given to the Allied Governments for data furnished to our engineers who designed the Liberty Engine, but it should not be forgotten that this engine is strictly an American product, having been designed for rapid production, standardisation and interchangeability of parts, factors not realised to the same extent in other designs. The benefit which this will have in increasing the effectiveness of our fighting contingents at the front can scarcely be over-estimated. The aviation engine is of course a high-strung piece of apparatus, one that must develop great power with minimum weight. The engine operates under full load and at high temperature practically all the time, so that its depreciation is relatively rapid.