Science Notes and News.

King Country Chronicle, Volume VIII, Issue 721, 14 November 1914, Page 3

Science Notes and News.

—» — THE ROMAN AQUEDUCTS

The Roman aqueducts were marvels nf architecture. The Anio was 43 miles long; the Mar bio.. 41, of which 38 miles wore on 7,000 arcades 70 feet high; and the Claudia was 47 miles long, the arches being 100 feet high. The aqueducts brought 40,000,000 cubic feet of water daily into Rome, and the various sections of the metropolis were supplied with water by -means of 13,504 pipes.

WHY EYES SHINE

Place a child (because the pupils of children are large), and by preference a blonde, at a distance of 10ft. or 15ft. from a lamp which is the only source of light in a room, and cause it to look at some object in the direction of tho lamp, turning the eye you wish to lock at slightly inward toward the nose. Now, put your own eye close behind the lamp-flame, with a card between it and .the flame. If you will then look close by the edge of the flame covered by the card into the eye of the child, you will see, instead of a perfectly black pupil, a reddieh-yetlow circle. If the eye happens to be hypermetropic, you will b-s able to see the red reflex when your own eye is at some distance to one side of the flame. This is the true explanation of the luminous appearance of the eyes' of some animals when they are in comparative obscurity. It is simply the light reflected from the bottom of their eyes, which is generally of a reddish tinge on account of the red blood in the vascular layer of the choroid back of the semi-transparent retina, and not light that is generated there at all. This reflection is most apparent when the animal is in obscurity, but the observer must be in the light, and somewhat in the relative position indicated in tlio above-described, experiment—that is, in the eye of the observer must be on the same line with the light and the observed eye. The eyes of nearly all animals are hypermetropic, most of them very highly so, so that they tend out the rays of light which have entered them in a very dive v ginß manner.

WH¥ HOT WATER CLEANS.

If our hands get dirty—and in the dusty conditions of modern life it seems to bo their almost constant state —one of the first desires we have is to get them clean. Should the dirt be anything other than simple dust, however, experience shows that cold water will not serve to cleanse the skin properly. Even if we use soap, cold water removes dirfc much less readily than water that is piping hot. Yet both hot water and cold water are equally wet.

A very profound law lies at the bottom of this strange condition, a law, however, which has only recently been entirely understood. This has to do with the movement of the molecules of substances, which have only a little power of motion in a solid, a great deal of motion in a liquid, and which are almost altogether free to move as they please in a gas. It is evident, thsn, that anything which liquifies a substance gives it a greater power of motion, or makes it move more easily. There is a constant layer of grease on o.ur hands. The skins of some people are more oily than others, of course, but in even those that have the driest skins, there is a considerable amount of natural fat that has exuded from the pores and the fat glands near them. It is to this layer of grease that dirt sticks. This is why our hands never really can be utterly clean, because there is always the oily surface and there is always dust in the air and on every article we touch. Cold water, instead of softening the grease that is on our hands, has the effect of chilling it, and chilling grease, as is well known, only makes it harder. Consequently, while cold water may take, off a certain amount of the dirt which has not become thoroughly ingrained into the oily layer of the surface of the hand, it only make the lower layer harder. In definite terms, it retards the molecular motion in the oil by lowering its temperature. Hot water, on the other hand, has a very rapid effect upon the residue of oily perspiration and dust. It melts the greasy layer, so that its motion is made much more rapid, so that the particles do not hold together as clcsoly and in consequence may be washed off much more readily. Soap, scda, and other cleansing preparations depend largely on the chemical compounds they make, which have in turn the power of hastening the revolving motions of the' atoms of dirt, and in actual scientific sense as well as in popular speech they "loosen the dirt."

A blast of heat which would he great enough to vaporise the grease, for example, would render washing unnecessary. This would not be possible on the skin, of course, for the heat required would burn the hand bub in the case of oily machinery a jet of superheated steam will rapidly cleanse dirty parte, because the heat will vaporise the grease and the blast of steam drives off the solid particles. It is this difference between tho effect of hot water and cold that makes "tubnight" just as important in summer, though one takes a daily swim; and that makes cleanliness so difficult a matter in tenements and houses where a supply of hot water is difficult to ■procure «. . r

THE PRINTER'S FRIEf*4D.

"There is a man ihc printer loves, and he is wondrous wise; whene'er he writes the printer man he dottcth ail his i's. And when he's dotted all of them with carefulness ami case, he

punctuates each paragraph, and crosses all his t's. Ui:on one sidcalone he writes, and never rolls his leaves; and from the man of ink a smile and mark 'inseit' receives. And when a question he cloth ask—taught wisely he hath been —he -cloth the goodly penny stamp, for postage back, put in. And thus by taking little pains, at trifling care and cost, assures himself his manuscript will not be burned or lost. So let a'l those who long to write take pa'tern by this man, with jet black ink and paper white, do just the best they can ; and then the printer man shall know, and bless them as his friends, all thronjjh li.'e's journey as they, go, until that journey ends." Correspondents plec.se note!