In these circumstances, it is not at all surprising to find that numerous firms have given considerable attention to the manufacture of the internal combustion class of engine, and many varieties, for a multiplicity of purposes, are upon the market. The limits of space effectively prevent my detailing the list of even the largest manufacturers; I will therefore content myself by referring to but one firm--Messrs. Vickers, Ltd.--who are now the largest manufacturers in the Kingdom. This progressive firm has grappled with the internal combustion engine problem from the earliest stages of the petrol engine to the latest forms of the heavy oil engine and its remarkable developments, and a large section of their establishment at Barrow-in-Furness is, and has long been, set aside exclusively for the design and manufacture of the heavy oil internal combustion engine. A very large staff of expert engineers has been selected for the work, while experiments with a view to improvements being effected in details are continually being conducted in the establishment. The result is that the development of this engine at the Barrow works has been attended with the highest success, a fact which is not widely known to the general public. I take it as a great compliment that permission has been given me in this book to refer somewhat in detail to the achievements of Messrs. Vickers, Ltd., in this respect, for, hitherto, publicity in connection with this section of the firm’s operations has been strictly withheld. One of the latest and, it might well be said, the most important developments in connection with Messrs. Vickers’ activities, is the Vickers patent system of fuel injection, which enables an engine of the Diesel type (that is, using heavy oil) to be successfully run without the use of an air compressor for injecting the fuel into the engine. Before the introduction of this system, an air compressor, with its attendant complication and weight, had to be used for the introduction of the fuel into the engine. The elimination of this compressor has resulted in considerable economy in weight, space, and attendance, which, it will readily be seen, is a step in the right direction, whilst the efficiency of the engine has also been improved. The disadvantages attendant upon the use of the air compressor were early comprehended by Messrs. Vickers, and they have spared no efforts (nor expense) in developing the system which has led to its elimination. The reader will require no knowledge of the subject to understand that the question of fuel consumption is one of the highest importance in any engine system, and, in regard to this point, Messrs. Vickers have made a special study, with the result that whilst the ordinary consumption in a Diesel engine with air compressor is ·41 lb. brake horse-power an hour (or 184 grammes _par force de cheval_), that firm have been able to reach the low figure of ·376 lbs. B.H.P. an hour (or ·170 grammes _par force de cheval_).