Page:Popular Science Monthly Volume 18.djvu/295

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mote. The salutary influence of children is equally marked with married and widowed persons, with men and women. The Swedish statistics may be brought in again to enlarge our knowledge on this point by showing the combined influence of marriage and age. According to these tables, the difference in the liability of married men and celibates, while they are still young, is very slight. The tendency to suicide then increases slowly among married men as they grow older, and at its maximum (at about sixty to sixty-five years of age) is two and one half times (26 in 100,000) what it was at the adult age (10 to 11 per 100,000). After the sixty-fifth year it diminishes. With unmarried persons, on the other hand, the tendency increases with almost a geometrical progression. At twenty-five years of age it is more than double (26 per 100,000) what it is with married persons of the same age (11 per 100,000), and at seventy years is eleven times as great (230 against 21 per 100,000); and after this period it goes on increasing as fast as ever, while the proportion for married persons is diminishing. The phenomena with women are analogous, but less marked. It is found, by comparing the statistics of the two classes, that the general increase in the tendency to commit suicide with advancing age can be almost wholly accounted for by this progression of suicides among the unmarried. The difference in the liability of the two classes may be partly explained by setting off the regularity of habit which married life and particularly the care for children induce with the irregularities to which the unmarried surrender themselves, of which the most damaging is drunkenness. Signor Morrelli says that drunkenness causes thirty-one per cent, of the suicides in Denmark, and that a similar rule prevails everywhere.


Artificial Lights.—The great point of difference between natural and artificial lights. says Dr. Javal, the French occulist, is the excessive feebleness of the latter. A lamp or a gas-jet makes an insignificant impression in daylight. The light of a million candles burning in a room would be vastly inferior in intensity to that of the direct rays of the sun. The pupils of our eyes are considerably larger in the most brilliantly lighted room than they are in daylight. We seek the brightest places of resort at night, and use the strongest lights we can afford in our homes, employing every means to make them stronger. Persons with imperfect sight are fatigued in working with artificial lights because the enlargement of their pupils gives full play to faults which are mitigated under the contraction of the aperture which a strong light induces. The spectra of all artificial lights, except the magnesium and electrical lights, are different from the spectrum of sunlight in that they are dark on the most refracted side, that of the blue, violet, and chemical rays. It may be that this quality compensates in part for the greater dilatation of the pupil which these lights require by reducing the amount of chromatic refraction which would otherwise take place. It does not appear, however, that any workmen prefer such lights to sunlight. It has been suggested that the presence of these rays in the electric light might cause it to be injurious. If that should prove to be the case, any evil effect might be remedied by shading the pencils with yellow-tinted globes. No complaint has been made, however, of bad effects arising from the proper use of this light. Those who have studied it most attentively have felt no inconvenience except when they looked intently at it without guarding their eyes. It is not intended to be used thus; and, if we judged by this criterion, the sun would be the worst of all lights. When the electric light was first introduced into the freight depots in Paris, the workmen complained of being dazzled by it. After some weeks, it was taken away, and gas was put in its place, when a general outcry went up against the darkness.


A Solar Machine.—The idea of applying the heat of the sun directly as a motive force has been entertained as within the limits of possibility for some time. A Frenchman, M. Mouchot, devised a machine, about two years ago, for concentrating the rays of the sun so that they could be made to perform some slight offices. M. Abel Pifre, an engineer associated with M. Mouchot, has carried on some experiments in Algeria with an adaptation of his machine which have had a promising degree of success. His apparatus