If he can recognize his father or mother or brothers and sisters at a distance of a hundred feet he can see far enough for all practical purposes. If he readily finds a small object like a pin or a small black bead when dropped on the floor, his sight is sharp enough at short range to serve his purposes. If his attention can be attracted by waving a hand or a little flag or a flower fifty or sixty degrees on either side of the direction in which he is looking, that is, two-thirds of the way to the side of his head, his angle of vision is sufficiently wide. If he can pick out from seven balls of worsted of the seven primary colors--red, orange, yellow, green, blue, indigo, and violet--the ball that matches another of the same color, he is at least not color-blind and has a sufficient sense of color for the ordinary purposes of life. It may be necessary to wait till eighteen months for a satisfactory color test. Color blindness, when present, is usually most apparent in a failure to distinguish between red and green, these two widely differing colors seeming to produce the same impression upon the color-blind eye. The child will be just as likely to choose a red ball to match the green one in his hand as to select another red ball. But repeated tests should be made before accepting color blindness as a fact, since sometimes the brain can be educated to discriminate between red and green even when the impressions have not the normal degree of difference. The tests for taste, smell, muscular sense, touch, and memory cannot be made with much thoroughness or satisfaction till two years of age, though observation will show a recognition by taste and smell of that which is agreeable and that which is disagreeable. Accurate tests of hearing cannot be made till the child is three or four, but it is possible when he is twelve months old to determine whether the hearing is normal or is seriously impaired, and it is very desirable that this should be done.