As one might expect, Messrs. Vickers, in bringing their engine to its present state of perfection, have, perforce, had a varied experience with fuel oils--and a considerable one, too,--for they have experimented with oils from all the well-known producing fields, and find that, under their system, practically any fuel oil which can be made to flow may be utilized in their engines--a fact which, in its importance, speaks for itself. The physical properties of the oils used by them have, naturally, differed very considerably. For instance, specific gravities have varied from ·810 to ·950 flash points from 100° Fahr., to upwards of 250° Fahr., whilst the viscosities, which the lay mind might well be excused for thinking of as “degrees of stickiness,” have varied from that of the ordinary kerosene (illuminating oil) to the thick asphaltic fuel oil which comes from Mexico. Readers may judge from this of the painstaking and difficult experiments that have been carried out in the Barrow works. The advantages derivable from the use of the Vickers system could not, obviously, be withheld from general use, and the firm have upwards of twenty licensees now manufacturing internal combustion engines under their designs. This fact, though not familiar to “the man in the street,” is known in the manufacturing world. [Illustration: 900 B.H.P. LOW DUTY VICKERS ENGINE FOR OIL TANK VESSELS] [Illustration: BACK VIEW OF ENGINE] Already a very large number of their engines have been constructed, the approximate brake horse-power produced by same being upwards of 337,600. These engines are of various sizes, ranging from 200 to 2,000 horse-power. The cylinders vary in diameter from 10 to 29 inches, and are arranged to work in groups to suit the power required, and may be either two-stroke or four-stroke cycle. The high temperatures set up in starting the engine are sufficient to ignite the fuel, the introduction of which in a finely-divided condition has been the object of so many experiments at Barrow; and so successful in this direction have Messrs. Vickers been that they are now able to deal satisfactorily, by careful adjustments of the engine to suit the various fuels, with the most troublesome oils. As already referred to, the elimination of the air compressor constitutes the chief improvement embodied in the Vickers type of engine, seeing that the greatest worry which the Diesel engineer has had to encounter has been this very compressor. Needless to remark, therefore, this feature alone strongly recommends the new system to the experienced man. Further, the power required to drive the compressor above-mentioned is considerable, so that economy is not one of the least results due to its absence. The principal advantages that can be claimed for the Vickers engine may be summarized as under-- 1. Safety in working. (Many accidents have been due to the use of the air compressor.) 2. Weight is saved. 3. Space is saved.