Simplification Has Limits.
In discussing form we saw that simple shapes, such as those of sticks cut from a cylindrical tree, are not so strong as the less simple forms of hollow cylinders. We found that a joist, of plain rectangular section, is not so good a burdenbearer as a girder whose section resembles the letter I. If a slide for a timber is to be built on a mountain side, a novice would suppose that a straight inclined plane would afford the speediest path for the descending wood. Not so. More speedy is a slide contoured as a cycloid, the curve traced by a pencil fastened to the rim of a wheel as the wheel rolls along a floor beside a wall against which the pencil presses.
Not all tasks are simple, so that it is often best to build and use a machine as complicated as a turret-lathe or a Jacquard loom. Whatever the inventor seeks first, last and all the time is Economy; to that end he adopts whatever means will serve him best, whether simple or not. Professor A. B. W. Kennedy, famous as a teacher of machine design, says:—
“Simplicity does not mean fewness of parts. Reuleaux showed long ago that with machines there was in every case a practical minimum number of parts, any reduction below which was accompanied by serious practical drawbacks. Nor is real simplicity incompatible with considerable apparent complexity. The purposes of machines being continually more complex, simplicity must not be looked upon as absolute, but only in its relation to a particular purpose. There are many very complex-looking pieces of apparatus which work so directly along each of their main branch lines that they are in reality simple. It is usual that the first attempt to carry out a new purpose results in a very complicated machine. It is only by the closest examination of the problem, the getting at its very essence, that the machine can be simplified. If a problem is only soluble by extremely complicated apparatus, it becomes a question whether it is worth having. Closely allied to simplicity is Directness. Certain transformations are unavoidable, but the fewer the better. In some cases they may be as indispensable as the abused middleman in matters economic. In the first machine to do something mechanically hitherto done by hand, the error is often made of trying to imitate hand-work rigorously. The first sewing-machine was, I believe, made to stitch in the same way as a seamstress. It was not until a form of stitch suitable for a machine, although unsuitable for the hand, was devised, that the sewing-machine was successful. The first railroad carriages were practically stage-coaches put on trucks, from which the present carriages have only very slowly been evolved.”