Scientific and Useful.

Patea Mail, 26 May 1882, Page 2 (Supplement)

Scientific and Useful.

RAINFALL. The Khasi Hills present the greatest rainfall in the world. Sir J. Hooker recorded upwards of 500 inches during a stay of nine months, and the total annual fall is about 524 inches. On the other hand, there are certain localities in which little or no rain falls ; the chief of these rainless regions being Upper Egypt, the Sahara, the desert of Gobi in central Asia, and the coast of Peru. As we recede from the hotter regions of the earth, either to the north or south, the rainfall, as a rule, diminishes, but the number of rainy days in the year increases ; so that, speaking roughly, it may be said that, where the rainy days are fewest, the amount of rain is greatest. COMPOSITION OF THE AIR. On accurately examining a given measure of atmospheric air, it was found that it contained about one-fifth its bulk of the gas oxygen and four-fifths of nitrogen. To speak with more accuracy, 100 volumes of pure air contain 20’8 vols. of oxygen and 79‘2 vols. of nitrogen. If, instead of a given volume, or measure, a given weight of air is examined, it will be found.that 100 parts by weight—whether grains, ounces, or pounds—contain 23 of these parts of oxygen and 77 of nitrogen.

PERCENTAGE OF CARBONIC ACID IN AIR. On the Thames at London, mean, -0348

In the streets of London ... ... *O3BO Prom the top of Ben Nevis ... .0327 From Queen's ward, St. Thomas’s Hospital ... ... ... ... ‘O4OO From the Hayraarket Theatre, dress circle, at 11.80 p.m. ... ... '0757 From Chancery Court, 7 feet from ground ... ... ... ... ’1930 From the Underground Kail way, mean, ... ... ... ... *1452 From workings in mines, average of 339 samples ... ... ... "7850 Largest amount in a Cornish mine 2.5000 COMPOSITION OF WATER. Let pure hydrogen be perfectly dried, and thnn burnt: hold over the jet of burning gas a cold dry glass jar, and the surface becomes rapidly bedewed, the moisture condensing in drops which trickle down the side, and may be collected. These drops are nothing but pure water, which has been produced by the union of the burning hydrogen with the oxygen of the surrounding air. Most of our ordinary combustibles —such as coal, wood, oil, wax, tollow, and gas —are rich in hydrogen, and they consequently produce water during their combustion. Hold a cold bright mirror near to a flame, and the moisture is instantly condensed upon its surface. THE THERMOMETER. The thermometer commonly used in this country is graduated according to a plan introduced by Daniel Gabriel Fahrenheit, a native of Dantzic, who settled at Amsterdam in the beginning of the last century, and became famous as a thermometer maker. In Fahrenheit’s instrument, the distance between the_ freezing and boiling points of water is divided into 180 equal parts, or degrees, and the zero or starting-point of the scale is arbitrarily placed 32 degrees below this freezingpoint. On the Continent another scale is commonly used, known as the centigrade scale, since the distance between the freezing and boiling points of water is divided into 100 degrees. The centigrade scale is now frequently used in scientific investigations in this country. As a given temperature is indicated by different numbers on the two scales, they are distinguished by addition of “ Fahr.” and ,f Cent.” to the readings, or simply by the initials F. and 0. AMOUNT OF LIGHT FROM THE SUN. From the surface of the sun, enormous quantities of light and heat are continually being radiated, or thrown out into space, in all directions. The earth, however, on account of its small size and its great distance, can receive but an extremely small proportion of the total amount which is thus shed. In fact, it is calculated, that our globe receives less than the two-thousand-millionth part of the total quantity of the sun’s light and heat. All terrestrial phenomena, which depend upon solar light and heat, are therefore effected by means of this extremely minute fraction of the sun’s stores of energy.

A PLAGUE OP SQXJIEBBLS.

North America seems to be incessantly troubled with living plagues. It is matter of common knowledge that the crops of the Western farmers are frequently destroyed by swarms of the Eocky Mountain locusts. A few months ago we had occasion to speak of a plague of frogs which sorely annoyed the inhabitants of Winnipeg, and now we hear of squirrels. Ordinarily the squirrel is an inoffensive little animal, whether he be of the wood or of the prairie. His impudence as an individual is remarkable. It is, however, more amusing than disagreeable. But the inhabitants of Arkansas know to their cost that, when united in swarms, squirrels become destructive enemies. Early last July it was noticed by sportsmen in the interior of the State that the squirrels were unusually numerous in the woods. Their bushy tails and quick, bright eyes were to be seen on almost every branch, and warnings were uttered of their probable early depredations. Autumn came on —the time of maturing cotton and ripening Indian corn. Then the spuirrels justified the warnings which had been issued against them. Leaving in myriads their haunts in the woods, they attacked the cotton and corn fields. Tearing open the balls of the cotton plants, they ate all the seeds and scattered the cotton on the ground. In the corn-fields they devoured the kernels on every ear. until nothing but the cob remained. So . serious were their ravages that the Arkansas farmers and planters became more than frightened by them. Happily, huwever, as a local account of their doings naively remarks, they began to migrate to Mississippi and Tennessee, and the boys had “ a good time” in capturing hundreds of them_ as they sought to cross the Mississippi river. Whether they wrought as much destruction on the eastern side of the stream as they did in Arkansas does not appear, but, for obvious reasons, the inhabitants of Mississippi and Tennessee are not likely to share the delight with which the people of Arkansas hailed their departure.