Obviously the easiest solution would be a means of transit, a tiny metal track, ubiquitous, traceable under cover of darkness across the trackless waste, with diminutive rolling-stock available at any point. But how to achieve this end? No one could deny but that the need was both immediate and pressing. Seemingly happy inspirations, as all the world knows, succeed more often than not in theory rather than in practice, and for this reason all credit is due to Miss Cooke in that the happy notion of utilising a Ford car, pure and simple, and of converting it into a light railway tractor materialised in as short a space of time as is humanly possible to convert thought into being, to fashion fact from fancy. Moreover, the advantages accruing from the idea were not limited to this one extent only, for quick to perceive the essential, Miss Cooke further devised a scheme whereby the vehicle, remaining entirely self-contained, was both convertible and re-convertible; that is to say, like the hare it could speed along the high-road to any given point or locality, where quickly transformed it would, like the tortoise, commence its slower and uneven progress on a diminutive line of rails, laid haphazard across some devastated area, unballasted, lop-sided, up and down, this way and that way. _Per contra_, its immediate task accomplished, and in proportion as the exigencies of modern strategy demanded further changes of _venue_, off would come the little tractor from its erst-while _voie-ferrée_, and shodding itself anew with road wheels and rubber tyres, away along the high-road once again to its ensuing sphere of tortuous rail-activity. [Illustration: A CREWE TRACTOR IN ROAD TRIM.] [Illustration: A CREWE TRACTOR AS LIGHT-RAILWAY ENGINE ON ACTIVE SERVICE. [_To face p. 130._] At first sight the casual observer might reasonably have been excused for puzzling his brain as to the exact nature of the contrivance, curious if compact, and neatly secured on the familiar Ford chassis. But on closer inspection, the salient features would resolve themselves into a fairly obvious entity; nor should a due meed of praise be withheld from the draughtsmen and engineers responsible for the successful evolution of the tractors on a sound and practical basis. At the outset, considerations such as height of centre of gravity contingent upon the loads likely to be carried over an uneven, narrow and diminutive track measuring but 1 foot 11-5/8 inches wide, length of wheel-base and corresponding ability to safely negotiate sharp curves, available tractive effort depending upon a coefficient of sliding friction between tyre and rail, all these appeared as obstacles not altogether easily surmountable.