Foreword by Sir Diarmuid Downs: Sir Harry Ricardo was an engineer, scientist, inventor and designer who had a profound effect on the world-wide development of the internal combustion engine. His achievements were repeatedly honoured throughout the automobile and aircraft industries during his lifetime. As a consultant engineer, Ricardo played a vital role in bringing about British victory in two world wars and made a major contribution towards the development of the internal-combustion engine for both automobile and aircraft use. Today, the company founded in 1917 by Sir Harry, Ricardo Consulting Engineers, remains the world's foremost internal-combustion engine research establishment, retained as a consultancy by most of the world's leading car manufacturers.