Not fifty years since it was a matter of the utmost difficulty to set an engine to work, and sometimes of equal difficulty to keep it going. Though fitted by competent workmen, it often would not go at all. Then the foreman of the factory at which it was made was sent for, and he would almost live beside the engine for a month or more; and after easing her here and screwing her up there, putting in a new part and altering an old one, packing the piston and tightening the valves, the machine would at length begot to work.[17] Now the case is altogether different. The perfection of modern machine-tools is such that the utmost possible precision is secured, and the mechanical engineer can calculate on a degree of exactitude that does not admit of a deviation beyond the thousandth part of an inch. When the powerful oscillating engines of the 'Warrior' were put on board that ship, the parts, consisting of some five thousand separate pieces, were brought from the different workshops of the Messrs. Penn and Sons, where they had been made by workmen who knew not the places they were to occupy, and fitted together with such precision that so soon as the steam was raised and let into the cylinders, the immense machine began as if to breathe and move like a living creature, stretching its huge arms like a new-born giant, and then, after practising its strength a little and proving its soundness in body and limb, it started off with the power of above a thousand horses to try its strength in breasting the billows of the North Sea. Such are among the triumphs of modern mechanical engineering, due in a great measure to the perfection of the tools by means of which all works in metal are now fashioned. These tools are themselves among the most striking results of the mechanical invention of the day. They are automata of the most perfect kind, rendering the engine and machine-maker in a great measure independent of inferior workmen. For the machine tools have no unsteady hand, are not careless nor clumsy, do not work by rule of thumb, and cannot make mistakes. They will repeat their operations a thousand times without tiring, or varying one hair's breadth in their action; and will turn out, without complaining, any quantity of work, all of like accuracy and finish. Exercising as they do so remarkable an influence on the development of modern industry, we now propose, so far as the materials at our disposal will admit, to give an account of their principal inventors, beginning with the school of Bramah. [1] 1 Samuel, ch. xiii. v. 21. [2] State Papers, Dom. 1621, Vol. 88, No. 112. [3] Lectures on the Results of the Great Exhibition of 1851, 2nd Series, 117.