Science.

Wairarapa Standard, Volume XX, Issue 2061, 29 April 1887, Page 2 (Supplement)

Science.

Magnets*

It is somewhat strange that the journals identified with the milling interests have never had much or anything to say regarding the use of magnets in flour mills. This cannot be because magnets are of slight importance, for many educated and intelligent millers know their great value. But it is, nevertheless, true that magnets are seldom mentioned in milling journals, and are still unknown in far too many mills large and small. To be sure there arc regions, though becoming few and for between, where the absence of wire-binding harvesters, and the exercise of unusual care in garnering, diminish the danger to reels and rolls from bits 0! metal; but oven under such conditions it would undoubtedly be a wise precaution and an economical measure to employ magnets. It is quite a common practice to fix them in gangs in the wheat spout, and if well done this will doubtless be effective for a while : but they soon become choked with captured fragments, and must be frequently cleaned if they are to do satisfactory work. In any event, they are not really cheap ; for if well attended they take valuable time, and if ill attended they become worse than useless. For instance, we were once in a mill where the shorts betrayed unmistakable traces of mctalic substances. The miller admitted their presence, but declared that he could not account for it. Did he use magnets? 11 Ob, yes, of course.” Yet when he showed them to us, he found to his surprise that they were either deficient in power or so loaded with broken wire, nails, screws, etc., as to be practically ineffective. We have also seen rolls the surfaces of which were cut and scratched to an extent which showed that they must have been regarded by the miller in charge as fit receptacles for miscellaneous hardware ; and how he could expect them to remain in perfect alignment and parallelism under such treatment is quite beyond our powers of conception. The demand, then, is for a device which will do its work well without constant watching and cleaning—that is, some arrangement in which the magnets are automatically and regularly cleaned. These points have been embodied in the”magnetic separator,” an invention which is almost infallible in detecting and arresting unwarranted mctalic intruders. Once in a great while something will make its way past a separator and leave its mark on the rolls, but a suitably protected closed spout, leading from tbe discharge of the separator to the first-break hopper, is almost certain to prevent such an occurance. Probably one half the magnets sold to millers are practically worthless for use in Hour mills. When tested they prove to be insufficiently charged, and hence have but limited power to attract pieces of metal. A good ten inch magnet should be able to lift a twelve pound weight and hold it, but we have seen many that would not hold one pound. The steel for a reliable magnet must bo of oven and close grain, by no means soft, for its power depends on this in a measure. It not infrequently happens that two pieces of steel of the same roiling will make magnets of different strengths, and it is oniy by years of study and experience that a manufacturer can be sure of always producing well charged magnets. He has to go through with many experiments, using different grades of steel, before he can toil which is best for bis purpose. It is therefore not to l;e expected that a good separator can bo bad for a song, although its price is not beyond the means even of a small miller.

First be sure that you need a separator, then go ahead and gel one of the first class. Don't be satisfied with anything less. This is true economy.

Earth Movements —Despite a popular belief to the contrary, it is not the ocean that changes, but the land winch undergoes alternate movements of elevation and depression. An earthquake is a phenomenon well adapted to destroy the faith of any person who feels one in the fixedness of the earth ; and such, by (he evidence, is the effect for the time on all who experience these shocks. Even the light pulsations which sometimes pass over parts of the United States occasion panic and excite a momentary impression that everything is falling over or sinking away; while the more violent shocks that are felt in earthquake infested countries produce indescribable terror; and such catastrophes as those of Lisbon and Caracas, and the more recent ones of Ischi and the Straits of Sunda.amountTo a demonstration that the reason for such terror is real, and that the continents also cannot escape the general law of change and perishability. Earth movements, the name by which these phenomena may be the most conveniently described, arc various, and comprise, so far as they are now considered, earthquakes, or sudden violent movements of the ground ; earth tremors or minute movements which usually escape attention by the smallness of their amplitude ; earth pulsasations, or movements which are overlooked on account of the length of their period ; and earth oscillations or movements of long period amMarge amplitude—like the shitting of levels of land masses—which attract attention from their geological importance. Some of these movements have only recently begun to attract attention. They are ail intimately associated in their occurrence and their origin.

A Torpedo Cannon Ball— The .l»e«./r Militairr gives us some particulars concerning a torpedo cannon ball invented by Captain Coudray, of the navy. Four years ago the captain presented his projectile (o the authorities who at onee ordered experiments to be made with it at (laves, near Eorient. We are told for some time past the modest inventor has been engaged in manufacturing his projectiles under the supervision of a special commision named by the Minister of Marine. At first it was found that all the projectiles discharged at the mean velocity of lod metres a second rebounded on si i iking the object at which they were lircd. Time was afforded to Captain Gourd ray to improve his invention, and it seems that, i t spite of much head shaking on (lie. part of the -hinnitx. he has succeeded in curing the defect complained of. The torpedo cannon ball, we are assured, now travels at the rate of lion metres a second, amt instead of rebounding on striking a ship, glides along its side, and never loses contact until it explodes. The last cannon balls constructed contain a charge of Id pounds of guncotton, although 2.3 pounds is said to be sullicient to blow up the biggest vessel. It is stated that these projectiles can be fired to a much greater distance than the Whitehead.

The /fwtit/announces that Prof, Korol, of Morges, in the Canton of Vaud, has discovered a natural gallery which goes right across the lower portion of the glacier of Arolla. in the Eringerthal, in the Valais. It constitutes a natural grotto in the heart of the glacier, and was explored to a distance of 2.V; metres (273 yards) by the Professor and some fellowmembers of the Swiss Alpine Chib from Geneva, Neucbatcl, and Canton of Vaud. The average width was from (I to lo metres, broadening out here and there to fully 23 metres ; the height varied from 2to metres. At Hie spot where the party stopped, (he cavern divided into two galleries, the exploration of which they reserved for another lime. . The glacier was found fo rest direct on the ground.

Diphtheria and Manure Heaps--df. I'erraud. Li/ihi Mnlir,il. I races the relation between manure heaps and niral epidemics of diphtheria. On mic occasion the disease appeared lie day rolluvine a cenernl -(:<>.■( ehsinine. Ih'arcic s 1 hat manure slued,| i.e kept ill I Ins d V. I 1I I of Slollc. ehl/eil with lilt mm in - i - s .11 .Iniel.-d ihal tin- llnid< li !. i awin I rum the solid matter.