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710 pursuing it. There can not be "might" or earnestness—of the best sort—in an uncongenial enterprise. It is not necessary that an occupation should be ardently loved, but it is indispensable that there should be some special fitness for a calling if the powers of mind are to be resolutely and effectually engaged. Medical men see a great deal of life, and nothing strikes the observant family practitioner more than the number of feeble, sauntering, and loitering minds with which he is brought into contact. No inconsiderable proportion of the common and some of the special ailments by which the multitude are affected may be traced to the want of vigor in their way of living. The human organism is a piece of physico-mental machinery which can only be successfully worked at a fairly high pressure. It will almost inevitably get out of gear if the propelling force is allowed to fall below a moderately high standard of pressure or tension, and that degree of tension can not be maintained without so much interest as will secure that the mind of the worker shall be in his work. It is curious to observe the way in which particular temperaments and types of mental constitution are, so to say, gifted with special affinities, or predilections for particular classes of work. The men who work in hard material are men of iron will, which is equivalent to saying that the men of what is called hardheaded earnestness find a natural vent for their energy in work that requires and consumes active power. On the other hand, the worker in soft materials is commonly either theoretical or dreamy. There is a special type of mental constitution connected with almost every distinct branch of industry, at least with those branches which have existed long enough to exercise a sufficient amount of influence on successive generations of workers. We are all familiar with what are called the racial types of character. It would be well if some attention could be bestowed on the industrial types, both in relation to educational policy and the study of mental and physical habits in health and disease.—Lancet.

Changes on the Moon.—A European astronomer, M. Jules Klein, affirmed, in March, 1878, that he had discovered evidence contradicting the generally received opinion that all action had ceased upon the moon. He claimed that he had observed a large depression, in the shape of a crater, newly formed to the east of the crater Hyginus, and that a large valley had been made south of the mountain called by Mädler the Colimaçon. His views were disputed, and it was said that he had seen, not something that was really new, but something that had been overlooked in previous observations. He defends the accuracy of his affirmation in a recent number of the "Astronomische Nachrichten" by producing evidence that the objects he describes had never been noticed, until he pointed them out, by astronomers who had made a constant study of the moon, and whom they could not have escaped if they had not been new. The original journals of Gruithuisen, which have just been published, bear directly upon the question. They are accompanied by the astronomer's original designs, which are of an astonishing fineness and accuracy. Among the designs is one including the crater Hyginus, with its great cleft, and Mount Colimaçon. The most minute details are given; but the depression in Ilyginus is wholly absent, as is also the valley south of Colimaçon, although every other furrow on that side of the mountain, of which Gruithuisen made a special study, is scrupulously given. M. Klein describes his object as a large funnel-shaped crater, from which a shallow ladle shaped valley extends toward the south, terminating in a small crater. The valley may be recognized, when it is not in shadow, as a gray spot. M. Klein believes, but does not undertake to prove, that nebulous clouds are produced on the moon which have no analogies on the earth; and that whoever examines the observations which have been made on the lunar formations from the time of Gruithuisen to the present will be convinced that changes for which we can not account are taking place on its surface.

The Ocean-Currents of Greenland and Iceland.—Captain N. Hoffmeyer, Director of the Royal Danish Meteorological Institute at Copenhagen, has published a summary of the facts ascertained in the recent deep-sea explorations of the Danish schooner