Page:Popular Science Monthly Volume 14.djvu/859

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on a white ground; the eye is thus in presence of the most absolute contrast which can be imagined. The third peculiarity lies in the arrangement of the characters in horizontal lines, over which we run our eyes. If, during reading, we maintain a perfect immobility of the book and the head, the printed lines are applied successively to the same part of the retina, while the interspaces, more bright, also affect certain regions of the retina, always the same: the result is fatigue. Last and most important of all, in M. Javel's estimation, is the continual variation of the distance of the eye from the book. The accommodation of the eye to the page undergoes a distinct variation in proportion as the eye passes from the beginning to the end of each line; and this variation is all the greater in proportion to the nearness of the book to the eye, and the length of the line. In order to avoid these injurious effects, M. Javel advises frequent intermissions during reading. To reduce the contrast between the white of the paper and the black of the characters, M. Javel recommends the adoption of a slightly yellow tint of paper. His third suggestion is to give preference to small volumes which can be held in the hand, which obviates the necessity of the book being kept fixed in one place, and lessens the fatigue resulting from accidental images. Lastly, M. Javel advises the avoidance of too long lines, and therefore he prefers small volumes, and for the same reason those journals which are printed in narrow columns. Of course, every one knows that it is exceedingly injurious to read with insufficient light, or to use too small print.


An Insect Ragman.—A correspondent of "Hardwicke's Science Gossip" tells of a very curious discovery he made last summer at Bellosguardo near Florence, viz., a veritable insect ragman. Having noticed what he at first took to be a little nest of spiders' eggs blown along a window-sill, he was led to examine it more closely, and found it to be a rather untidy, fluffy ball, about the size of a large pea; further, that it was moving along of its own accord, stopping now and then for a second, and again resuming its journey. It was soon discovered that the ball of fluff was borne on the back of a little insect somewhat resembling the larva of the dermestes, and that the mass was composed of cobweb held on the creature's back by being twisted about in and out among the long hairs on the upper surface of the body. The insect was about one quarter of an inch in length, and bore on its head a pair of forceps about the size of those borne by the common earwig, but its purpose was very different, "for to my amazement," says the author, "I noticed that, each time the creature paused, it was to pick up, with these forceps, some dead ant or portion of a dead insect; and these fragments were picked up so deftly, and in so droll a way did the creature turn its head round and carefully arrange his treasure on his pack, that I was forcibly reminded of the chiffonniers in France and Italy, with their hook and their basket, and of the 'ole clo'' and his pack in England. . . . For more than two days I kept it in a small glass-lidded box, supplied it with 'ole clo,' and watched it constantly collecting and packing; but I never saw it feed, and one morning I found that a large ant I had supposed to be dead had attacked and eaten the creature, scattering the fluffy pack and its contents all over the box." Some weeks after this the author received a note from a friend at Vevey, who from the description recognized the "chiffonnier," two of which, she says, "came toward me, on the table in the garden where I was seated reading, collecting and packing as you have described." From a friend at Bellosguardo he also, on his return to England, received an account of one she had found, and of which she thus writes: "I had half a mind to send you one of those scavenger or 'ole clo'' insects; but could not arrange anything that would insure its arriving alive. The pack on his back is much less choice than the others, consisting of parts of the bodies of dead flies, spiders' cobwebs, etc., while he himself is much smaller. I feel quite sure it is his food he collects, because the first night I put him under a tumbler he ate the wings of his fly, the only ornamental article in his collection. He is exceedingly fond of sugar—has eaten, I am sure, twice his weight—and has just added two small dead ants to his load, under which he staggers visibly. His pack is held on by long, projecting hairs, and likewise secured and strengthened by cobwebs."