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to turn it with a definite velocity when the exterior current is flowing, and, if the outer circuit is suddenly broken, the machine is seen to acquire an increasing velocity, showing that the mechanical force applied to it, being no longer capable of going off as electricity, spends itself then in augmenting the velocity of the moving parts of the machine.

On the other hand, if the machine is kept at a certain speed of revolution while the outer circuit is broken, and the circuit is then suddenly closed, the speed instantly diminishes, showing that a portion of the force turning the machine changes into electricity.

These experiments show that, whether the machine be active or passive, there exists always a state of equilibrium between the expenditure of mechanical force and the production of electricity.—Quarterly Journal of Science.



XIV.—Preparation in Biology.

THE parable of the sower has its application to the progress of Science. Time after time new ideas are sown and do not germinate, or, having germinated, die for lack of fit environments, before they are at last sown under such conditions as to take root and flourish. Among other instances of this, one is supplied by the history of the truth here to be dwelt on—the dependence of Sociology on Biology. Even limiting the search to our own society, we may trace back this idea nearly three centuries. In the first book of Hooker's "Ecclesiastical Polity," it is enunciated as clearly as the state of knowledge in his age made possible—more clearly, indeed, than was to be expected in an age when science and scientific ways of thinking had advanced so little. Along with the general notion of natural law—along, too, with the admission that human actions, resulting as they do from desires guided by knowledge, also in a sense conform to law—here is a recognition of the fact that the formation of societies is determined by the attributes of individuals, and that the growth of a governmental organization follows from the natures of the men who have associated themselves the better to satisfy their needs. Entangled though this doctrine is with a theological doctrine, through the restraints of which it has to break, it is expressed with considerable clearness: there needs but better definition and further development to make it truly scientific.

Among reappearances of this thought in subsequent English writers, I will here name only one, which I happen to have observed in