“Among the first things a practical engineer should know, and among the last things he will, after becoming such, forget, is that in handling water within pipes he has a fluid which, while it is flexible to the greatest extent and is susceptible of the influence of power, or force, of greater or less intensity, and while it may be drawn from below and raised to the heights above, can be turned to the right or to the left at will, and while, with a seeming docility which is as flattering as it is deceptive, it bends itself to the will of the engineer, still there are some things it will not do, and which all the complicated appliances of the engineer have as yet failed to compel it to do. When inclosed within chambers and pipes, to an extent that fills them, it will not permit the introduction of an added atom without bursting its bounds. While inclosed within long lines of pipes it will not suddenly start into motion, or when in motion suddenly come to a rest, without shocks or strains more or less disastrous; and so, while it seems to be handled with the greatest ease, it is only in the manner it chooses to go, and all mechanical appliances not designed with reference to following these imperative laws are sure to meet trouble, if not disaster. In other words, when an unyielding force meets an unyielding resistance, their coming together means a shock to all about.”