NOTES ON SCIENCE, MECHANICAL INVENTIONS, ETC.
FLIES AS SANITARY INSPECTORS. The Sanitarian records an instance of flics acting as sanitary inspectors. In ono of the trooms of a residence in an American city ■offensive odours wore detected, but their * exact source could not be located. The carpets were raised, and a carpenter engaged to take up the entire floor. At this moment a friend who chanced to come in suggested that an appeal be made to tho instinct of the fly Two blue-bottles wero brought from a neighbouring stable, and the doors and windows of the room closed. The flies soon, settled upon one of tho cracks in the floor, and, when the boards were raised at this point, a decomposed rat was found. THE RAILWAYS OP THE WORLD, According tc statistics recently published in a German journal on the railway enterprise of tho world, the aggregate mileage at the end of ISB4 was 290,750 miles. Europe claimed of this total 117.091 miles; Asia, 12,757 ; Africa, 4075 ; America, 145.73S ; and Australia, 7486. Not less than (50 per cent, of the whole mileage of tho world in in English-speaking countries. Australia has the
largest amount of railway accommodation in proportion to population, and tho United •JStates and Canada come next. The cost of ponstructing the universal railway system is estimated at £4,500,000,000. The highest expenditure was in Great Britain, whero it amounted to £41ICS per mile, as compared with £24,797 in Belgium, £'24 92S in France, £21,041 in Germany (State railways), £20,555 in Austria, £16,449 in Russia, anil £12,650 in the United States. bell's latest INVENTION. Professor Alexander Graham Bell and his cousin, Dr. Chichester Bell, have reoently made a very remarkable discovery, which hey think is quite as important as the ransmission of the tones of tho human voice F through the telephone. They have discovered that a falling jet of water or a flame of gas burning in a room reproduces every word spoken and every sound uttered within a Lgiven distance. When two people join iu Conversation in a room in the evening, the ''gas which burns above their heads repeats every word they say, and sounds uttorecl in Jhe vicinity of flowing water produces vibrnBons. It is well enough understood that whatever can repeat the waves of air produced by any loud sound will repeat the sound itself. It is the principle of the telephone. But in the telephone tho original impulses are repeated instantly, and die away for ever. In this new apparatus, assuming that it really does all that is described, the waves are not reproduced in that form, but their efleot on a jet of water, long known to be sensitive to such impulses, is caught by instantaneous photography, and permanently recorded on a glass plate ia the form of minute irregularities of surface. By suitable apparatus these elevations and depressions, .which correspond to pulsations of air, are retranslated into air waves, and the voice is heard again. The water, or liquid of whatever kind it may be, is coloured with bichromate of potash. If it Were perfectly clear it would not answer, because the light used in photographing would pass through without resistance, and no xecord would be made on tho tablet. The water is coloured for photographing, and the jet is made to fall obliquely on a glass plate. The water spreads . itself out on the glass plate and runs off. It is the water so spread out that is to be photographed as it passes. 'Words spoken causes the jet of water to vibrate; the vibrations in the jet causes corresponding vibrations in the film of water as it breaks and spreads on the glass plate and runs off. A ray of light is passed through
that film and through the glass plate to a sensitive tablet behind. The vibrations in the liquid film are reflected in the variations of intensity of the impression made on the photographic tablet. Speaking continues, the jet keeps running, the film keeps passing over the plate, the recording tablet keeps moving as the film keeps moving, and the light, passing through this film to the tablet, makes a record of the speech far more accurate than any verbatim report. WHO WAS THE INVENTOR OF THE TELEPHONE? | This question has been revived, and has Recently been giving rise to a good deal of correspondence in the newspapers ; and like all subjects of the kind, it will doubtless give rise to a good deal more before it is settled to the satisfaction of everybody. But whoever bad the honour cf discovering the principle of the telephone, the Italians seem recently to have taken a step which ought to solve the problem for all time. Not content with possessing Galvani, Volta, and Pacchinotti in their niches of electrical fame, they have just erected a statue at Aosta which bears the following significant inscription :—" Innocenzo Maiizetti, inventor and maker, in the year ISG4, of the first telephonic apparatus, in occasion of the inauguration in 1886 of the railway line uniting Italy with the old town of Aosta. The Association of Mechanical Industry and Kindred Arts of Turin." What the Americans will have to say to this in their patronage of Bell, and the Germans in view of the discovery made by Philip Reis at Frankfurt in 1858, may be looked forward to with some interest. — Electrician. A NEW LIFE BUOY. * For a considerable time the use of the old circular life buoy for saving life has been strongly critised by all those who practically understand it. For when it is dropped into the water to a person unable to swim, it is entirely unmanageable, and is more frequently the cause of drowning than of saving life. A life buoy of a horizontal description has often been suggested by those who have studied the best means of saving life. We now call attention to a new life buoy for ships, boats, and quays, which ha 3 been invented and patented by Mr. Alexander Smith, president of the Arbroath Swimming Club. The buoy is of a longitudinal construction, has contro handle with buoy on each end, elliptical, oval, or round shape, and can be made cither airtight or solid. The airtight buoy has two airtight compartments, and is made so that either air of other gases can bd inserted with the mouth, or otherwise, if required, through a small nozzle. All round the sides, aud over the top and bottom, is a hand rope, fastened with eyelet ringc, projecting out, 80 that they can easily bo gripped at any part. At each end there is a thimblo hole where a lino can be attached to. Each end and arms has a sort of handle, and when going to be put into the water, the person grips the end with one hand and the centre with the other, It can then be pitched from fifteen to twenty yards by an ordinary person, as they only weigh from Sib to 101b. When it is pitched to a person in the water, they may grip it at any part ; but no sooner baa a person a hold than the centre comes to him, and all they have to do is to pass both arms over the centre, and they are in a safe position at once.
The telephone between Vienna and Brunn, ' a distance of one hundred miles, has commenced working, and is a complete success. The system employed ia that of Kvsselberghe, which allows oi the use of ordinary telegraph wire, Preparations are already been made for the establishment of regular telephonic communication between Vienna and Pesth, a distance between two and three times as great as between Vienna and Brunn. — Electrician. . Water and steam pipes arc now made of paper. Strips of pap-r, the width of which correspond with the length of one pipe section, are drawn through melted asphalt, and wound upon a mandrel. When the pipe has cooled the mandrel is withdrawn, and the inside is covered with a kind of enamel, the nature of which i* not made public. '1 lie Outside is painted with asphalt varnish and dusted ovor with sand. The pipe is about hiif an inch thick, but is said to resist '2000 pounds internal pressure. When tempering cold chieels or any other steel articles, heat to a very dull red and rub with a piece of hard soap, then finish heating and harden in clear, cool water. The potash of the soap prevents the oxygen of the atmosphere from uniting with the steel and forming rust or black oxide of iron. The article will need no polishing to enable the colours to be seen. This will be appreciated wncn tempering taps, die», or various complex forms not easy to polish. Never " upset" a cold chisel. It is sure death to the steel. Recent experiments have been made with a view of recovering the tin from waste and scrap tin plates by means of an electric process which is also said to be applicable to the treatment of tailings, slug and many kinds of refuse. Dynamos are nsed to generate the electric current, which is pa«sod through the j solutions in which the tin cutting* cr miuitjg «st iffs arc deposited. These :uc connected i with the positive pole and tne tin withdrawn , from the tin cutting!, or the gold withdrawn , from other substances which may be under ! treatment.