Page:Popular Science Monthly Volume 25.djvu/441

Rh the books of the United States Mint the names of at least one thousand collectors who receive yearly the issue of the mint, with special proof-polish. In New York, alone, during the year 1882, thirty-nine collections were sold at public auction, and brought, in all, $68,441.36. Several of our large cities have numismatic societies, some of which are designated as numismatic and archaeological societies; and a number of periodicals devoted simply to the interest of numismatics obtain a satisfactory circulation.

Seasonal Variations of Rheumatism.—The records of rheumatic cases in the London Hospital fail to show any clear relation between the prevalence of the disease and particular climatic conditions. Dr. Henry S. Gabbett has compared the graphic curves representing the numbers of cases observed for nine years, and remarks a general similarity between them. In nearly every case a wave is noticed beginning to rise at the opening of summer, and reaching its highest elevation in July or August; then comes a temporary check or fall, followed by a rapid ascent till the summit is reached, at the end of autumn, when a steady fall occurs through the months of December, January, and February, till a low level is reached, which continues nearly even till about the beginning of the next summer elevation. The curves for different years do not appear to be affected by variations in the character of the seasons from which it is possible to make any deduction respecting the influence of variations of temperature or of conditions of moisture. Accepting Messrs. Buchan and Mitchell's division of the London year into six periods, each having a climate peculiar to itself, "we find that rheumatism was most prevalent in the annual damp and cold period; next in the damp and warm period; cases were about equally frequent in the two periods characterized respectively by heat and cold; below these comes the dry and warm period; and lowest of all, as regards the frequency of the disease, the period described as dry and cold.... It does not, however, necessarily follow that there is any etiological connection between the above facts; the periodical prevalence of the disease may possibly be independent of conditions of climate." Dr. Gabbett draws the conclusions, with a little more confidence, that the disease is neither most prevalent in the coldest months of the year, nor least prevalent in the warmest; that it does not occur with greatest frequency in those months in which the daily variations of temperature are greatest; that, although there is a certain correspondence between the rainy periods and the times when rheumatism is common, it is not close enough to point to any necessary connection. But cases of the disease are very numerous at that period of the year during which there is usually a coexistence of low temperature and heavy rainfall—viz., the end of autumn.

Shall we put Spectacles on Children?—In a paper with this title Professor Julian J. Chisholm, M. D., of the University of Maryland, makes a plea for providing children with the means of counteracting their congenital or acquired defects of vision. According to the traditions, the need of spectacles is an indication of old age, and so the world interprets it. A better knowledge, however, is diffusing itself among the medical profession, and from them to the public. While advancing years may be a factor, it is only one of many causes inducing defective vision. The action of the perfect eye conforms to the law of optics that, unless a lens focuses accurately on the recipient surface, the image made must be more or less imperfect. In front of the lens there is a broad, circular ligament of the eye, which presses against it, and, when objects at a short distance are to be looked at, by the action of a muscle (the ciliary), the compressing ligament is relaxed, so that the lens, its natural elasticity responding at once to the relief, becomes more convex, and is, therefore, in condition to focus more powerfully light coming from near objects. What is called accommodation, or ability to change the focus, is, then, a muscular act. When the accommodating muscles are temporarily enfeebled by diseased conditions of the system at large, they do not lift off sufficiently the flattening band, or they are too weak to keep up the continued action for the relief of lens pressure; hence we often find children recently recovered from an