Page:Popular Science Monthly Volume 21.djvu/61

Rh gilt window-plate is hinged; it may thus be adjusted to any position and inclined at will according to the direction from which the light comes.

A simple and moderately satisfactory stereoscope may be improvised by unscrewing the concave eye-pieces from an ordinary opera-glass, and looking through it at the stereograph, which must be held about six inches from the centers of the object-glasses and parallel to the line connecting these. Vision by this method, however, is very uncomfortable if the stereograph be large. The instrument is a crude Helmholtz stereoscope, but it needs adjusting-screws at both ends of each tube to make it entirely satisfactory. The only objection to Dr. Holmes's instrument is the absence of adjustment; but, despite this defect, it is deservedly used everywhere in our country. Quietly and unselfishly he has done far more for the stereoscope in America than has ever been credited him by those who enjoy the fruits of his spontaneous and unpaid ingenuity.

 

HEN shall we have anthropometric laboratories, where a man may from time to time get himself and his children weighed, measured, and rightly photographed, and have each of their bodily faculties tested, by the best methods known to modern science? In the January number of this "Review" I endeavored to show the advantages of photographic chronicles maintained from childhood to age, and how they should be made and preserved; in the present memoir I propose to briefly speak upon the anthropometric and medical facts that might properly be recorded by the side of the photographs in the family records to which I there referred. I shall endeavor to define the scope of what may be effected in this direction, partly by accurate apparatus now extant, and partly in a rougher and less effective way, owing to the present want of appropriate apparatus. In doing so the instrumental and other desiderata will be pointed out that seem most easily capable of being supplied, if the attention of a few persons interested in the matter could be brought to bear on the subject Two things are at present needed—a desire among many persons to have themselves and their children accurately appraised, and an effort among a few scientific persons who have the special knowledge required for the purpose to systematize the methods by which this could best be done.

There appears at length to be a somewhat general concurrence of opinion that the possibilities of a child's future career are more narrowly limited than our forefathers were fondly disposed to believe. I 