We are told that "the use of travelling is to regulate imagination by reality, and instead of thinking how things may be, to see them as they are." Hence it has been, we may confidently aver, for the purpose of seeing things as they are that we have availed ourselves of this opportunity to fathom in some measure for ourselves the abstruse art of shell-manufacture as practised in Crewe Works. The imagination, however morbid and obtuse, can hardly fail to be stirred when pondering the rotund and rudimentary profile of the rough shell-forging lying with all its latent possibilities, recumbent in the lathe; ultimately in its finished form _c'est cela_,[6] the shell we meditate, _qui va nous débarrasser des Prussiens_; thanks now to that generous impulse which prompts our gallant gunner-men, good fellows all, possessed of "mildest manners with the bravest mind," to unravel for us the all-absorbing mysteries of that sphere of "war's glorious art" in which they themselves excel, reality will regulate our questioning imagination as we follow them to the dim seclusion of some cleverly camouflaged gun-emplacement. [6] _C'est celui-la_, etc., said of the Tsar, Nicholas II., when visiting Paris in 1896. We have already seen that the motion of a shell is rotary as well as forward, this rotary motion being brought about by the joint instrumentality of the grooving of the bore of the gun and of the copper band on the shell. Another and very important function performed by the copper band approximates to that of the piston-ring of a locomotive cylinder, which prevents the passage of steam from one side of the piston to the other. Concomitantly, the copper band, turned a fit in the bore of the gun and jammed into the rifling, is designed to obstruct the passage of the propellent gases beyond the base-end of the shell; these gases are naturally imbued with a habit or hobby of gnawing away, or eroding, any metal surfaces with which they can come into contact, so that the further they can penetrate up the bore of the gun, the more material damage that will ensue, and the rifling becomes proportionately erased or eaten away. Further, owing to the fact that the degree of heat generated by the ignition of the propellent charge is obviously most intense in the area most adjacent to the base of the shell, erosion becomes patently more pronounced here than in other directions; consequently as the area in which the propellant gases are exploded increases, so the pressure exerted by these gases decreases, the net results of these considerations being loss of accuracy and of velocity.