710 



THE POPULAR SCIENCE MONTHLY. 



pursuing it. There can noi be " might " or 

 earnestness of the best sort in an uncon- 

 genial 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 inconsider- 

 able 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 ma- 

 chinery 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 ob- 

 serve the way in which particular tempera- 

 ments 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 say- 

 ing that the men of what is called hard- 

 headed earnestness find a natural vent for 

 their energy in work that requires and con- 

 sumes 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 con- 

 nected with almost every distinct branch of 

 industry, at least with those branches which 

 have existed long enough to exercise a suffi- 

 cient amount of influence on successive gen- 

 erations of workers. We are all familiar 

 with what are called the racial types of 

 character. It would be well if some atten- 

 tion 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 evi- 



dence contradicting the generally received 

 opinion that all action had ceased upon the 

 moon. lie claimed that he had observed a 

 large depression, in the shape of a crater, 

 newly formed to the east of the crater Hy- 

 ginus, and that a large valley had been made 

 south of the mountain called by Miidler the 

 Colima9on. 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 astron- 

 omers 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 as- 

 tronomer's original designs, which are of an 

 astonishing fineness and accuracy. Among 

 the designs is one including the crater Hy- 

 ginus, with its great cleft, and Mount Coli- 

 ma9on. The most minute details are given ; 

 but the depression in Ilvginus is wholly ab- 

 sent, as is also the valley south of Colima- 

 9on, 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 fun- 

 nel-shaped crater, from which a shallow ladle- 

 shaped valley extends toward the south, ter- 

 minating 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 sur- 

 face. 



The Ocean-Cnrrents of Greenland and 

 Iceland. Captain N. Hoffmeyer, Director 

 of the Royal Danish Meteorological Insti- 

 tute at Copenhagen, has published a sum- 

 mary of the facts ascertained in the recent 

 deep-sea explorations of the Danish schooner 



