In his recent lecture at the Royal Institution, Mr A. A. Common, the treasurer of the Astronomical Society, pointed out that the old method of eye-observation in telescopic work would probably in the near future give way to automatic records on sensitive dry plates by means of photography. He also pointed out what extreme variations existed in the amount of light emitted by different celestial objects, contrasting with the blinding glare of the sun the small quantity of light received from a faint star. The latter he described as being equivalent to the twenty-thousandth part of the light given by a standard candle seen from the distance of a quarter of a mile. It is not a matter for wonder, therefore, that the most sensitive dry plate which would yield a photograph in daylight in the smallest fraction of a second, should require an exposure of two hours, or thereabouts, when used for recording the existence of one of these distant orbs.
Signor Ferrari, after making observations on between six and seven hundred thunderstorms which occurred in Italy a few years back, has noted that every thunderstorm is connected with a barometric, hygrometric, and thermic depression. A German scientist who has interested himself in the same line of inquiry, states that the danger of a building being struck by lightning has increased in his country during the past half-century from three to five fold. He attributes this increase of danger to impurities carried into the atmosphere from factory chimneys, the number of which is constantly increasing.
A new electric alarm-bell for use in places where highways and railways cross one another has been invented in the United States. On approaching such a crossing, the wheels of the train depress a heavy trigger placed by the side of the rails. This trigger sets in motion a flywheel sufficiently powerful to turn the armature of a small magneto-machine. The current thus generated rings a bell at the cross-road, so that wayfarers have an audible reminder of the near approach of a train. Of course the same result might be brought about with an electric battery. But the magneto-machine has the advantage of requiring no attention, and of not being affected in any way by changes of temperature. Its bearings can be provided with oil-cups, so that it will act for months together without supervision.
Professor Ewart lately read a paper before the Royal Physical Society of Edinburgh, in which he stated that from examinations of specimens of ‘whitebait’ sent into the London market during the past year, he had come to the conclusion that the much esteemed little fish consisted of sprats and herrings, about sixty per cent. of the former to forty per cent. of the latter. The origin of so-called ‘whitebait’ has always been such a disputed point that the Professor’s remarks are particularly interesting. He also pointed out that in Canada, sprats are extensively tinned as sardines. As we some time ago pointed out in these pages, a similar trade has been for a long time carried on at more than one place on the south coast of England. We may mention that the authorities of the South Kensington Aquarium are about to introduce herrings into the tanks under their control, in spite of the fact that all such attempts, in inland places at least, have hitherto failed. We trust that their endeavours will be crowned with success.
Messrs Fairbairn and Wells, Manchester, have lately much improved their screw forging machine. By this method of making screws, it is claimed that much greater tenacity, ductility, and durability are obtained in the finished product; for the fibres of iron, instead of being cut through, are pressed and bent round to the shape of the thread. In short, the machine rolls out the screws, instead of cutting them out. We have lately seen photographs of some of these screws which have been partially eaten away with acid, for the purpose of showing the fibrous nature of the metal. It is curious to note how the fibre is bent in and out as it follows the direction of the thread on the screw. This method of manufacture is said to present advantages apart from better quality. The screws can be more quickly produced at a less cost, and there is a great saving of material, for nothing is cut away to waste.
The results of a curious but very important test as to the accuracy with which chemists, druggists, and others make up prescriptions committed to their care, has recently been presented to one of the London vestries. Fifty prescriptions were sent out to ordinary druggists, to co-operative stores, to ‘doctors’ shops,’ and to certain traders styling themselves drug Companies. The mixtures made were afterwards analysed, to find out how nearly they agreed with the prescriptions they represented; but in order to give a liberal margin for error, it was resolved not to put a black mark against any one, if the chief constituent were within ten per cent. of the right amount. Notwithstanding this margin, no fewer than seventeen out of the fifty mixtures were incorrectly dispensed. In one case the principal drug was less by eighty-five per cent. than the amount ordered, while in another it was fifty-seven per cent. in excess. The chemists and druggists came out best in this strange competition, as only six per cent. of their prescriptions had to be called in question. Next came the co-operative stores with twenty per cent. of error; then the ‘doctors’ shops’ with fifty per cent.; and lastly the drug Companies, who are credited, or rather discredited, with seventy-five per cent. of errors.
OCCASIONAL NOTES.
THE ROOSEN METHOD OF PRESERVING FISH.
We have already noticed the method recommended by Professor Cossar Ewart of preserving fresh fish with boracic acid and salt. Mr Roosen of Hamburg has patented another method, which was lately tested in Edinburgh. The process consists in the salmon being placed in an air-tight compartment among a solution of boracic acid, salt, and water, and a heavy pressure being applied, the solution penetrates and thoroughly disinfects the fish, which are prevented from decaying, and retain all their strength and nourishment. On the 15th of February, a steel barrel, made for the purpose, and capable of holding about three hundred pounds of fish, was filled with salt water containing about fifty per cent. of boracic acid, and into this compound five splendid salmon, fresh from the Tay, were placed. The air having been entirely withdrawn, the barrel was hermetically sealed, a pressure of six atmospheres, or ninety pounds to the square inch, being applied. After standing for seventeen days, the barrel was opened on the 4th of March, and all the salmon were found in as fresh and healthy a condition as when they were first placed among the solution. The flesh of the fish was of a beautiful colour, and could not be distinguished from that of a fresh salmon placed alongside of it, while the blood began to flow freely immediately on the salmon being cut up. The salmon was served up at a luncheon, on the following day, in different forms of cooking, and the general opinion was that the new method of preservation was upon the whole successful. The fish was of good flavour and colour; it could be separated in nice flakes, and the curd was well preserved.