SCIENCE NOTES.

Otago Witness, Issue 2968, 1 February 1911, Page 76

SCIENCE NOTES.

Magnetic Plant.— TheV* has been discovered' in the forests of India a plant which possesses astonishing magnetic power. The hand which breaks a leaf from it immediately receives a, shock. At a distance of 20ft a magnetic iseedle is affected by it, and it *> e ouite deranged if brought near. The energy of this singular influence varies with the hour* of the day. At the height of its power about 2 o'clock in the afternoon, it is absolutely quiescent during the night. —Preserving Spiders' Webs.—> Naturalists employ an interesting method to preserve all kiods of spiders' webs. The ■webs are first sprayed with an atomiser with artists' shellac, and then, should' they be of the ordinary geometric form, they are pressed carefully against a glass plate, the supporting strands being at the same time severed." After the shellac has drjed the plates carrying the web 3 can be stored away in a cabinet. Even dome-shaped webs may be preserved in their original form! by spraying them with shellac and them allowing them to dry before their removal from their supports. Many spiders' webs axe very beautiful, and all are characteristic of the species to which they belong, so that, from a scientific standpoint, their permanent preservation is very desirable. — Harper's Weekly. —Scourges of the Human Race. — The fly, the flea, and the mosquito are the veritable scourges of the human race in the diseases they carry. The fly carries diseases which decimate the native population of the African highlands; the mosquito spreads malaria, the most übiquitous of tropioal diseases, and is suspected of propagating yellow fever as well; and the flea spreads plague. In the last case there is usuallv only one kind of flea, pulex cheopis, which spreads the infection, and the other fleas which might spread it—the Ceratophyllus fasciata and the Typhotoosylla * musculi—are not very partial to jaiman blood, though the second will take 'o it more readily than the first- Happily "ar the white man' and the dwellers in fanperate climes, the range of most of Ihese death and disease-oarrying insects is /united to the tropics.—E. S. Grew, in the Daily Graphic. —The Creeping of Rails. — Not only do rails creep, but an American authority tells us that "on lines running jiorth and sr-uth, the western rail 'creeps' Easter than the eastern rail—that is, this strange movement of the rail towards the south is more marked in one rail than in the other on the same track. Furthermore, it has been noticed that on such a line the eastern i-ail wears out the faster. Both of these points can be explained by the motion of <he earth as it turns from the west towards the east. Everything that has free motion is Bragged after the whirling globe; every wind that blows and every tide that moves feels the influence, and a train going north or south is pulled over towards the east, and naturally presses the eastern rail most heavily. The western rail, being relieved' of its share of weight, 'creeps' more freely and quickly. It is also noticed that the wheels that run on the eastern rail wear out first." —The Rain-tree.— The rain-tree of Peru grows very large, is rich in leaves, and is called toy the Indians tamaicaspi. It has the power of collecting the dampness of the atmosphere and condensing it into a continuous and copious supply of rain. In the dry season, ■when the rivers are low and the heat great, the tree's power of condensing seems at the highest, and water falls in abundance from the leaves and ooze-, from the trunk. The water spreads aro: nd in veritable rivers, part of which fii;Vrs into the soil and fertilises it. These riibrs are canalised, so as to regulate the course of the water. It is estimated that one of the Peruvian rain-trees will on the average yield Sgal of water per day. In a field measuring: 3250 ft each' way can be grown 10,000 trees, and if we allow for evaporation and! infiltration these collect 29.531. gal of ram for distribution daily. The rain-tree can be cultivated with very little trouble, for it seems indifferent as to the soil in which it grows. The tree increases rapidly, and resists both extremes of climate. —The Serviceable S'ot Machine.— Some of the smaller European towns of Economical habits have been complaining because thev are obliged to light their rtreets all night for the benefit of a few belated citizens, and have been trying to discover a method whereby the citizen who needs to have his pathway lighted in the small hours of the Bight shall pay the cost himeelf. In osae of the streets of a small Gwnan town, such a system has actually keen, put into operation. Ine street it. k little over half a. mile lon*, and it provided with nine lamps. At each end of the £.treet is a ponny-in-the-slot machine, and whenever anyone wishes to light up strvfll', he has merely to drop in a ten-

pfennig piece, which turns on the current I for 12 minutes. This allows him ample 'time to walk the length of the Btreet ; The street is normally lighted until 10 o clock. Thereafter the prepayment meter must be resorted to. —The Electric Eye.— Professor Rosing, of the Institute of Technology, St. Petersburg, is announced to give a public lecture on a discovery which he claims to be one of the most remarkable ever made by a scientist. He declares that, after 15 years of incessant labour, he has succeeded in constructing an electro-telescopic apparatus which has all the virtues of what might be termed an "electric eye," and which will enable the fortunate owner to see anything and anyone he chooses. By an adjustment of the apparatus an employer sitting in his office will be able at will to "see" other parts, of the building and watch his unconisoious employees at work. A man will be able , to sit at home and witness a theatrical per- ' formance, or arrivals at a railway station, or any even,t of interest that may be happening a long distance away from the observer. Professor Rosing claims that a general who uses this invention will be able to observe the movements of the enemy as well as the movements of his own forces. He promises to give a full explanation of his invention in the near future. —Electricity on a Liner. — The fitting of the, new Olympic has not as yet 'been completely detailed for cation. But she is to go "one better" than the Mauretania. Comparatively few can grasp the significant part which electricity plays in this ship. Apart from the 70,000 horse-power of the turbines which propel the ship through the water, the electrical power, which is supplied by Jour generators, represent an additional 2144 horse-power. Electricity is used not only for illuminating the ship at night, but for a multitude of other purposes, such as operating the lifts, of which there are two for passengers use? eight for baggage and mails, and two smaller ones in the pantries. Electricallydriven cranes and winches Are also provided, and 6300 electric lamps give the enormous total of over 100,000 candle-power. For heating the first-class quarters 60 electric radiators have been fitted, to say nothing of some 43 heaters in the bathrooms. Numerous electric fans are used for ventilating the various rooms, and are so arranged that they can supply either warm or cool air according to the weather. In the kitchen one range alone has a frontage of about 60ft, and includes a roaster with four vertical spits rotated by an electric motor, these spits bein.fi capable of dealing with half a ton of meat at a. time There is also a smaller roaster with three spits, driven in the same manner. In the bakery electricity is employed to operate a large dough-making machine capable of making bread for at least 3000 persons. Some idea of the size of this vessel may be obtained' when it is mentioned' that, over 200 miles of wire and cables are fitted throughout the ship. The e ectrie bell and telephone installation on the Mauretania surpasses anything .hitherto attempted in connection with ship work. Bell pushes ; are placed over everv bed, and altogether | 1208 bell-pushes have been fitted m the ' various cabins, etc., while telephones, ot ; which there are upwards of 100, are to be I found in numerous .parts of the ship. Apart from the Marconi wireless telegraph outfit, I means have been provided for coupling the i ship up to the city telephone exchange j when lying alongside the landing stages at i Liverpool °or New York. Four electric I searchlights are carried, and in addition to ; the usual complement of life-buoys which ! every ship carries, two special buoys have [ been provided' for use at night. These, '■ upon bieng released by -pressing a button .'automatically, light a flare upon striking ; the water. ' The electric installation ot tnis j vessel represents about £65,000. i Good Rat Poison. — Since the recent introduction, specially ■ sanctioned by the Local Government Board, ! of the campaign against rats in London and East Anglia, many substances have been suggested as efficient rat poisons ; but the fault of many of them is that they are dangerous to "human beings if articles oi food become contaminated. It is therefore ' worth note that the United States Agrioul- ; tural Department recommend barium carbonate as the cheapest and most effective : destroyer of rats, and that in the smail I quantities used in this process, the compound is harmless to larger animals. It I lias the further merit that the animals j usually leave the premises, before dying ! in search of water. The bait, is prepared j by mixing one part of the barium carbonate with about five parts of oatmeal, and adding enough water to form a stiff paste, and the chemical can also be used by spreading it on bread and butter.