In the planning of machinery, notwithstanding the fact that power will be obtained at a minimum of expense, all contrivances which economise force will be highly valued. We have been increasingly valuing them ever since steam first became important as a source of motive power. Early machines in the Patents' Museum at South Kensington exhibit the most extraordinary recklessness in the waste of power. Considering the feebleness of the motive force available, one would have expected that every means would be sought to minimise friction. But instead, the force was transmitted by contrivances which, to a modern eye, seemed deliberately contrived to introduce as much friction as possible. Every year brings out fresh inventions for the avoidance of friction: and still we are but upon the very threshold of the subject. It was only in 1904 that a party of railway engineers was entertained by a patentee who wished to show them the saving in coal per train-mile which can be saved by a new bearing for passenger coaches, and the superior smoothness (which is of course a factor in the economy) of their running. Hardly any vehicle except a bicycle or a trotting buggy is yet constructed with any serious attempt to save friction at the axles. The number of industrial machines to which ball-bearings might be applied with great economy of power is enormous. But ball-bearings are very little used. It is probably considered as yet that the saving in coal would not pay for the working expenses connected with them and with other improvements. But as machinery is further improved economies at present merely theoretical will become practical and remunerative. In a hundred years' time we shall certainly be able to make generally profitable the use of many devices as yet applicable only to delicate and exceptional machines, and shall be able to use much power which at present runs to waste. Every time a locomotive is stopped there is a great waste of power in the operation of the brakes, because it is not worth while to adopt any contrivance for utilising it. It disappears, as heat, and is lost. Many similar wastages could be cited, and engineers would scoff at the citation, on the ground that the loss is not worth saving. But it will be worth saving a hundred years hence. We shall not be able to afford any waste. The world will have to be worked, as we say, "for all it is worth."