SCIENCE NOTES.

Otago Witness, Issue 2391, 28 December 1899, Page 58

SCIENCE NOTES.

—In the courae of his introductory address, in the opening of the twenty-sixth session of the evening classes at the Textile department of the Yorkshire College, Professor Beaumont gave an account of the new photographic method of preparing textile designs, invented by Jan Szezepanik, which he had re'eently been studying in Paris. The object jof the appliances, it was explained, was by j [mechanical means to enlarge the artistic | sketches of the designer, and to transfer the j '(dosign to ruled or point paper, marked with prilliona of dots arranged in the order proper por the development of the pattern in the Szczepanik printed the design by a photographic process on sensitised paper, Jand by his method the process of applying Aha weaves was governed, not by the skill of jthe artist or his assistants, but by -natural jQawa. Inaccuracies in shading were thus <made impossible, for the change in the weave fas absolutely identical with the toning of the [negative. Designs which now took weeks, [and even months, to prepare for the loom, Lwould by this new method be mechanically Ljvorked out in a few hours. For instance, [in six hours a design in silk tapestry, 176 square centimetres, or about 35 square inches, 'an extent had been prepared. It might be ' 'imagined that this ingenious and novel in- | lyention was calculated . to have an important j ."influence upon the branches of the weaving j 'industry, relating to the manufacture of all i elaborately-figured fabrics, especially if the I designs worked out photographically were ' legible for all practical purposes. It, was re- ' teognised, of course, that there must be limi- j Rations to its utility, as there were to all me- j jchanical and automatic appliances. Yet, if | it could be employed in accelerating the proycess of designing large patterns, it should {have the serious attention of all who desired 'lihe further development of the weaving industries. It was a mistake to think that, if jfche invention became commercially useful, jfche snhere of the designer would be consider- " »bly restricted. In the long run, innovations jpf this kind, though at first they might disuocate certain branches of employment, enriched in industry in whose interests they had jbeon introduced. The place of the designer, )the brain-worker in textile factories, could )iot be assailed by inventions of this kind. , — Magnalium is the name of a. new alloy 'of alummium and magnesium, discovered by CDr L. Mach', which is said to possess valuable '{properties. The addition of magnesium in not exceeding 30, and not less than •jLO, parts by weight to 100 parts by weight Jof aluminium 'imparts to the latter metal /properties which, in the pure condition, it does not possess, without raising its specific i (2.64) ; on the contrary, | slightly lowering it, since the specific \ (Jgravity of magnesium (1.74) is even less than j)that of aluminium. The addition of magjTiesium produces an alloy which is harder, and is easier and eleanei to work than pure Jtaluminium. Turning produces a ou,rface ( as bright as a mirror, and shining like silver, •Vthe metal coining off in long spiral turnings. , ( The alloy files clean and regular, without tearking or choking the file, as aluminium does. jODeep and narrow screw threads can be cut on J-it. and very clean holes can be bored out. ,The colour of the metal resembles silver more \Jthan aluminium, and it takes a high polish. jJThe hardness and strength of the alloy are considerable; the hardness can be varied by [•varying the proportions of aluminium. An 'addition of heavy metals is not only unnecessary, but is positively' injurious, since this deteriorates its working properties, and increases fats specific gravity. Previous attempts to janafco* useful alloys of aluminium and magjnesium^ are said to have failed, owing to the 'Aluminium not being pure. This point is »f great importance, and aluminium made Ly san electrolytic process must be used. — Electrical Review. } — Analysing the accidents to machinery ijwhieh have come unde? the cognisance of an insurance company, Engineering fehows that though valves and valve gears still 'ratain their bad pre-emiuence. the figures for Jthe present year prove that in certain direc!ttions past experience is having its effect on constructors. Thus failures from spur gearing, iwhich in former years have almost equalled /those from the valves, are now substantially % 3ess frequent. This is largely due to the snore general adoption of rope-driving, but 'the substitution of steel for cast-iron gear jwheels and the more freo'uent use of machined Jeeth are having their effect. Air pumps and >their accessories seem, on the contrary, to he increasingly troublesome; and it docs seem to persuade makers that no packing ■frings are required in sueb pumps. A simple groove bucket is cheaper, and gives quite as tood a, vacuum, though it is difficult to per-

suade many people that this is the case. If air pumps are designed so as to have loose pieces inside them, it is essential, if breakdowns are to be avoided, that the pumps should be opened and examined every half year; but it is far better to avoid the necessity by improving the construction. Packing rings are not needed; bucket valves can be dispensed with; and foot valves, with their grids and guards, can be secured in place with using a single internal bolt or wedge. Cylinder failures would seem to be increasing. This, no doubt, arises from the great increase of initial steam pressure which has marked the profress of ingineering di'ring the past few yours. lost of the failures have occurred in the large flat surfaces of slide-valve client?, or in the exhaust passages. They are apparently due quite as often to improper provision for extension as to .lack of strength. Cracks also often occur at the corners of the steam ports where the latter enter the cylinders, and are mainly due to a lack of stiffness in the metal beyond the part to which the cylinder cover is secured. The workmen in charge of electrical machinery are, according to Engineering, not so well up to their work as those in charge of steam plpnt. This was. perhaps, to bo expected, but may be trusted to right itself as time goes on. In some cases defects have arisen from inferior design in the first instance, but in others from absolute neglect. Other defects referred to relate to the construction of the motors and machines themselves. Incompetent brokers, it would seem from Engineering, are still engaged in the sale of second-hand boiler?, which they guarantee on theit own responsibility as suitable for any pressure the purchaser may desire; whilst certain owners still object to lay off their boilers once a year for an adequate inspection. The Manchester Insurance Company's inspectors make several ordinary inspections per year in addition. In one case a. vertical boiler was discovered with the safety valve tied down with a piece of rope, under the excuse that the spring was weak. The nianager responsible, when remonstrated with, declared insurance companies to be all humbug ! — The New York Electrical Review gives particulars of a recently-invented electrical and chemical fire alarm apparatus, which gives its indications when the atmosphere becomes so vitiated with smoke that it will not support the combustion of a gas flame. In the interior of the apparatus a small gas flame constantly warms a thermoslatic bar, the electric circuit through the apparatus being normally open as long as the flame holds out to burn. If the air in the apartment in which the apparatus is installed becomes vitiated with smoke, the little flame goes out, and the thermostatic bar, cooling off, closes the circuit and eives the alarm.

—In the manufacture of artificial ice two methods are usually employed : in the can method the cooled brine surrounds thin metal cans within which is enclosed the distilled water to be frozen in one „ system ; in the plate method the cooled brine or ammonia itself circulates in coils between hollow plates, say 10ft x 14ft in area, on the outside of which the ice forms in the water tank. In the can system blocks weighing 3001b will be frozen in from. so to 60 hours; in the plate system the ice forms 14in thick over their area in from nine to 14 days. ' The .can system is more usual for ice vendors, since the supply <-f ice blocks is continuous, bub the product cf the plate system costs less, although the plant costs more.

— The Cassier Ma.gazine Company of New York have published a special Electric Railway Number of several hundred pages, lavishly illustrated. As showing the remarkable progress of electric traction, the number is full of interest. In the short period of about 10 yeara, which span the life of commercial electric railway work, phenomenal results have been obtained. From the few struggling lines of the late eighties the growth has been such that to-day there are in the United State 3 alone more than 40,000 electric cars, running over nearly 15,000 miles of track, and yielding profitable returns on the enovmous capital investment of 1500 million dol-, lars.

— Recognising one's voice through the telephone makes it doubly hard to realise that the voice one hears over the telephone is not the voice of the person who is talking. It seems almost exactly like the real tones, drawn out thin and small and carried from a long distance by some mechanical means, but it isn't. When one speaks into the instrument, a little diaphragm, like a, drumhead, begins to vibrate, and each vibration sends a wave of electricity over the wire. These waves set up a mimic vibration in another diaphragm at the opposite end, which jars the air and produces an imitation of the original voice. This is not a scientific explanation, but it is the fact.

— Repeated attempts have been made to find a supposed effect from the moon on one temperatures. The reasoning is as follows : If we take the mean temperature for a few days at the time of new and full .noon, wo would obtain double the effect by subtracting one from the other. The latest effort of this kind has just come to hand, and was made with observations in London and at Blue Hill. Mass. The most remarkable le6ult was that while the full moon seemed to have power to cool the air in London, it ha« just the reverse effect in this country. In one lunation in this country the full moon was 29deg hotter than the new, and in eight lunations, for 88 per cent, of the time, the full moon, was markedly warmer than the new. How is it possible to reconcile these extraordinary results with what has been said above? It should be noted that it is absolutely impossible for the moon in one part of its apparent diurnal revolution about the earth to cool the air and in another part to heat it. It studying a mass of statistics to obtain a suspected connection between dissimilar phenomena, it is verj essential that three principles, at least, be distinctly borno in mmd — (1) That there should be data enough. "One swallow does not make a summer." (2) It should be possible to show by a priori reasoning how the relationthip may exist. By the statistics the ancients weie Xierfectly justified in th>iir teaching that the

earth was stationary and the whole universe revolved about it. Millions upon millions of such coincidences could not establish the true law. (3) The data must be homogeneous — that is, all sources of modification or variation must first be eliminated before study upon a suspected law or relationship can be begun. Just what influence the moon may have upon the electric -condition of the atmosphere may be considered in doubt. It is a common belief, on Long Island Sound, that no thunderstorm can come up while the tide ebbs ; also, there seems good evidence to show that there are more thunderstorms during new than full moon. We may be absolutely certain that the moon has no appreciable effect on any commonly-recognised meteorologic element. — From Popular Science (U.S.).