SCIENCE NOTES.

Otago Witness, Issue 2527, 20 August 1902, Page 64

SCIENCE NOTES.

— One of the Scientific American etaff has devised a very simple and inexpensive Apparatus for cutting initials, monogram?, and ornamental borders or bands on glass Wrticles, such as tumblers, bottles, hand mirrors, etc., with emery powder. When a letter or the libo is to be cut in the glass, (the glass may be held stationary by any suitable means, and then all that is uecesfcmry i 6 about 3lb of medium-grade emery fcod a funnel having a tube from 4ft to sft long and iin in diameter. The initial is cut through a paper stencil, which is (fastened to the glass with mucilage, or' held %n place by rubber band?. The emery, falling through the tube and striking on the exposed glass, will cut it quite rapidly, and /three or four runnings of the emery will form the cut sufficiently deep. It ■nay be stated that the stencil should be a ."trifle larger than the desired cut in the Iflaas. To cut an ornamental band on a goblet, tumbler, or bottle, the work should toe rotated elowly about 2in below the funnel kube. The turning, of courbe, may be done fey hand; but this will be somewhat t'.voBorne, and thus tend to lessen one's interest 5n the work. A boy with a little skill can rig up an old clockwork to do the turning, or the device may be constructed firm pnaterial found about the house. It consists of a suitably-mounted spindle, having jt block of wood or a large cork on one ,end to fit snugly in the tumbler so as to Support it, and also secured on the spindle is a drum, conveniently a largo spool, from /which a cord extends to connection with a fixed double pulley and a movable double toulley.to which the actuating weight is attached! If it is not convenient to procure pulleys, plates of metal, or even of wood, ■nay be pierced with holes, through which ,the cord may pass; but, obviously, pulleys are preferable because of the smaller friction and wear on the cord, which last may jbe a small fish line. When it is desired to inspect the progress of the. work, the- flow of emery may be cut off by a small cork attached to a string. When the string is Boosened tho weight of the emery will force rthe cork into the upper end of the funnel 'tube. The spindle should be provided with n crank for convenience in rewinding the feord, and during the rewinding the work of the emery may continue. — Complaints have again and again been made as to the vibration caused by the Central London railway. Few people are tiware, perhaps, of the smallness of the objectionable motion, but Mr Charlee Davison, in the June Knowledge, supplies some particulars. He says: — "In the solid stone or floors in the basements and in the walls /themselves, it .was rarely found to exceed one or two ten-thousandths of an inch, and such vibrations-, even if they recurred at the rate of 15 per second, would in all probability escape notice. On the higher floors, however, the vibrations have an amplitude .•which may amount to, though it seldom exceeds, a thousandth of an inch, but it is these vibrations, when their frequency is over 10 per second, that have given rise to such widespread annoyance." .The instrument by means of which these motions are recorded bas a degree of sensitiveness which may be judged "by the fact that records are clear I . y given of every footfall of a horse ■when distant more than 1000 yds" !

According to a recent consular report X remarkable phenomenon occurred last year in Naples, and in tlie neighbourhood generally of Vesuvius This took the form of rain which was c'.iargcd so hcaM'.y with hydrochloric acid that considerable dwmagc lo vegetation was the result. Tlio volss.no is always 'pouring ou^ f rom ' ls summit a cloud of steam, and it is kn« w<i that tins vapour i« charged with ac 'd r\halatmn = : but thoro fcconib to ho im pn uou- r«<or<l Df this acid contaminating the r.iiiifa'.l The nhenomcnon lasted for abcut a mouth in Ihe spring of !a=t year, and during tin-, -' period the leaves and buds of the spruiiting vine§ £§{• .Oftu&eU to shrivel jp. and had

the appearance of being burnt. The cereals grown in the villages adjacent to the mountain also suffered severely from the acid rain, and the 'mischief reached as far as Palma, near Nola, where hazel-nuts are grown in large quantities for export. The«e nut plants were practically ruined, all the young shoots being destroyed. By an old law sufferers from volcanic action can. get a remission of pai't or even the whole of the land tax., and there are many applicants for relief on account of this acid rain.

— Cassier's Magazine for June contains an interesting article on lightning. The old question used to be how to protect buildings against lightning — lightning rods br none, solid rods or hollow rods ; and on the latter point men like Faraday and Sir William Snow Harris took opposite sides and waxed wroth, each telling the other h» knew nothing about the subject. To-day little or no attention is given to this matter, and it is generally realised that as regards where lightning will strike we must take our chances, which, according to the statistics are about 1 in 100,000, of being stuck. The old idea that lightning will never strike twice in the same place has been pretty well exploded by the actual facts, and there is reason to assume that if lightning- strikes a given point once it may be expected to strike there again, rather than at «ome other contiguous place. While there is no cor tain immunity from lightning when it prevails, attention is called to the great desirability of persevering in efforts to resu«e-itatr-those who have been rendered insensible by lightning strokes, as recoveries haye 1 iepeatedlv been made of persons supposed to be dead, after more than an hour's effoits. Tho statistics also show that there is no immunity from lightning in a feather bed, in a house, or in a clo«ct, and that knives and the like do not attract lightning. For those who are inherently dreadful of lightning the only comforting suggestion that can be offered it, to rememoor that if one lives to see the flash ha is safe for that time i

— The adaptability of the gasoline marine engine to special environments can be no better illustrated than by citing: the conditions in Bocas del Toro, United States of Colombia. This town is surrounded by a number of bays and lagoons, which are lined with banana plantations. No frc*h water is available except that which is eauprht on the roofs of the houses", and salt water b<-m^ ruinous i-ct stc-am boilers, a steam launch may be- opevatr»d for only a slioit tune without being lad up for repans. About eight years ago two gasoline engines weie introduced, and they prc\ed them^Uos to be so well adapted to the conditions that at present there are over 40 gasoline, launches employed as tugboats for towing banana lighters to central points whero tho fruit is transferred to ocean steamships. An en terpu=ing planter scoured an export fiom one of the Amenean factories, and installed a complete repair shop especially adapted to gasoline engines. These tugboat* are employed going from plantation to plantation gathering up the fruit, which, on account of its perishable nature, must bo transferred in the 'horte^t possible time to tho &lnp«. j There are at prc-ent 35 of one mako of ' gasoline engine in use in this di->tuot. The j gasoline is shipped to the tugowner? in ' 210ga'l drum-, and the small .spue offur-ied in transport is especially in its fa\our as a fuel, since there is no coal obtainablein the market, and all of it mu-t be shipped .from tho United States.— X W. Kobert.s. "in the Engineering Magazine.

If Yorn Children' are subject to eionp watch for the fiist symptom of the d'-ea'o — hoar-enps--. If Chamberlain"-* Cough Re-mod v is L'lwn as fooii as» the child be

comes ho.ir-r-. tho attack can be aiertrd. Kv< i. .'if' i tin crcupy cnugh has appeared thy att.uk (.in always l>c prevented by H>%.i!-f tln-> r>.r.-"iU. It i- al'o in\ aluablo foi cokU and v. hoopme; oiujrh It always cures, tuid cure? ftun.kly. All dealers sell it.