THE MONTH: SCIENCE AND ARTS.

In a lecture at the Royal Institution, Dr Tyndall has made known the results of a long series of experiments on fog-signals, all involving more or less of noise, and demonstrating that the noisiest are the best. Mariners in a fog are helpless: no lights, no cliffs, no towers can be seen, and they must be warned off the land through their ears. So in conjunction with the Trinity House and the authorities at Woolwich, the Professor fired guns of various kinds and sizes, and very soon found that a short five-and-a-half-inch howitzer with a three-pound charge of powder produced a louder report than an eighteen-pounder with the same weight of charge. Thereupon guns of different forms were constructed, and one among them which had a parabolic muzzle proved to be the best, that is in throwing the sound over the sea, and not wasting it to rearward over the land. Then it was ascertained that fine-grained powder produces a louder report than coarse-grained; the shock imparted to the air being more rapid in the one case than in the other.

Experiments made with gun-cotton shewed conclusively that the cotton was ‘loudest of all;’ and ‘fired in the focus of the reflector, the gun-cotton clearly dominated over all the other sound-producers.’ The reports were heard at distances varying from two to thirteen miles and a half.

When the fog clears off, the noisy signals are laid aside and bright lights all round the coast guide the seaman on his way. Some years ago the old oil light was superseded by the magneto-electric light, and this in turn has given place to the dynamo-electric light, which excels all in brilliance and intensity. In this machine the required movements are effected by steam or water power; and when the electric current is thereby generated, it is conducted by wires to a second machine, which co-operates in the work with remarkable economy and efficiency. Readers desirous of knowing the improvements made in the dynamo-electric machines by Messrs Siemens, and the experiments carried on in lighthouses, should refer to the Proceedings of the Institution of Civil Engineers for the present session.

Particulars of a galvanic battery of extraordinary power have been brought to this country from the United States. Instead of the carbon plate commonly used as one of the elements in the cells, it has a copper plate coated with lead and platinum; and a blowing apparatus is so combined that a stream of air can be blown through the acid liquid with which the cells are filled. The effects of this aeration are remarkable: the galvanic current is rendered unusually powerful, and a large amount of heat is developed. The way in which these effects are produced is not yet satisfactorily made out; but that this battery offers a new and potent means of investigation to chemists and physicists cannot be doubted.

An account of an exclusively metallic cell has been given to the Royal Society by Professors Ayrton and Perry of the Engineering College, Tokio, Japan, in a paper on ‘Contact Theory of Voltaic Action.’ They took strips of platinum and magnesium, which were in connection with the electrodes of the electrometer, and dipped them into mercury, and immediately saw evidence of a strong current. The experiments were continued with much care until the Professors felt assured that ‘the electro-motive force obtained was about one and a half times the electro-motive force of a Daniell’s cell.’ ‘It may be possible,’ they remark further, ‘by mechanical or other means, or by using another metal than magnesium, to give constancy to this arrangement; and as its internal resistance is extremely small, the cell may be of great practical use for the production of powerful currents.’

In a discussion about Iron at the meeting of the Iron and Steel Institute, one of the speakers shewed that it was not so much quality of metal as mechanical structure that constituted good iron. He took certain railway bars and planed them, whereby he was enabled to examine their structure, and he saw that some of the rails contained much cinder, which accounted for their showing more signs of wear than others. On sifting the shavings and passing a magnet over them, all the iron could be taken out and the quantity of cinder ascertained; and not until this cinder could be thoroughly got rid of would the manufacturer be able to produce good iron. The same defect had been noticed in Swedish iron made for a special purpose; and there was reason to fear that manufacturers made more haste to send iron into the market than to produce the best quality. Fortunately, a few scientific men have introduced improvements which will in time abolish the rule of thumb that has too long prevailed.

The manufacture of bricks from slag is still carried on at the Tees Iron-works, Middlesbrough, by machines constructed for the purpose. The slag, ground into sand, is mixed with lime, squeezed into moulds, and each machine turns out about ten thousand bricks a day. Being pressed, these bricks present advantages over ordinary bricks: they are uniform in size and thickness; do not break; occasion less trouble to the bricklayer and plasterer; require less mortar; and do not split when nails are driven into them, whereby carpenters are saved the work of plugging. Another important fact, which the labourers will appreciate, is that the weight of a thousand slag bricks is one ton less than the weight of a thousand red bricks; and as regards durability, we are informed that the longer they are kept the harder they become.

An invention which simplifies photography out of doors may be said to have claims on the attention of tourists and travellers, as well as of professional photographers. To carry the bottles, liquids, and other appliances at present required necessitates troublesome baggage; but Mr Chardon of Paris shews that all this may be avoided by the use of his ‘Dry bromide of silver emulsion.’ This preparation, a mixture of collodion and the bromide, will keep an indefinite time in bottles excluded from the light, and does not suffer from varying temperatures. Specimens carried to China, and back by way of the Red Sea, underwent no alteration; an important consideration for travellers and astronomers who wish to take photographs in tropical countries. When required for use the bromide is mixed in certain proportions with ether and alcohol; the plates are coated with this solution, and as soon as dry are ready for the photographer. They require no further preparation, and retain their sensibility through many months. The image may be developed immediately or after some weeks, according to circumstances; in proof of which photographs taken at Aden have been developed in Paris. But a very small quantity of water is necessary, and the image may be transferred to a film of gelatine or a sheet of paper at pleasure, which lessens the risk of breakage, and the plates may be used for fresh pictures.

An account has been published of the disturbance and destruction which the telegraph lines in Germany underwent during the widespread storm one night in March 1876. The destruction was so very great, that had the storm occurred during a political crisis or a war, the consequences might have been much more calamitous. This liability to derangement has in nearly all countries led practical minds to conclude that underground telegraphs are preferable to lines carried on posts through the air; and the German government have laid underground wires from Berlin to Mainz (Mayence), a distance of about three hundred and eighty miles, which will afford excellent means for comparing the two systems.

Vast as are the forests of the United States, Americans are finding out that they are not inexhaustible. The annual product of ‘lumber,’ which means timber in all its forms, is estimated at ten thousand million feet, a quantity sufficient to make a perceptible gap in the broadest of forests. Among the heaviest items of consumption are the railways with their eighty thousand miles of sleepers, to say nothing of ties, bridges, platforms, and fences. The average ‘life’ of the wood when laid in the ground is from four to six years; and each year’s renewal is said to use up one-sixth of the enormous product above mentioned. These facts have led some thinking constructors to reconsider the national objection to precautions, and they now advocate the use of preserved timber, and have invented a method of preservation. The principal part of the apparatus is a large air-tight iron cylinder one hundred feet long, into which the wood is run on rails; all the openings are closed; steam at a high temperature is forced in, and the process is maintained until every part of the wood is heated up to two hundred and twelve degrees. The steam is then driven from the cylinder; heat is applied; then a vacuum is produced, and ‘many barrels of sap’ pour from the wood. Creosote oil is then forced into the cylinder. ‘Every stick is at once bathed with oil. The wood, being in a soft somewhat spongy condition, the fibres porous, and the pores open, absorbs at once the hot penetrating oil. If the wood be of a porous character like pine, it absorbs all the oil required in the first flow without any pressure; but if the fibre be solid and close and the timber of a large size, a further pressure of from sixty to one hundred and fifty pounds is needed to make the impregnation complete.’ This process reminds us of one on a somewhat similar principle which was noticed in this Journal for November 25, 1876.

In an address to the Royal Geological Society of Ireland, Sir Robert Kane remarked on the activity prevailing among the geologists and chemists of that country in investigation of their mineral resources. The search for fluorine in rocks has had favourable results; and the discovery of phosphoric acid is regarded as an indication of the extent to which organic remains were included originally in those mineral masses. Certain beds described by geologists as lower Silurian and Cambrian, destitute of fossils, nevertheless contain such traces of phosphorus as shew that they must have been formed in seas rich in organic life. These facts, as Sir R. Kane shewed, are of special interest in Ireland, where, owing to the rareness of those newer formations which furnish the valuable coprolite beds of Cambridge and Suffolk, such sources of agricultural wealth are absent; but where the older strata being so largely developed offer resources for discovery of accumulated organic remains which may be turned to good account in fertilising the soil.

Professor Boyd Dawkins, F.R.S., in discoursing to the Manchester Geological Society, mentioned the discovery of fresh evidence of the antiquity of man. Certain caves in Cresswell Crags, on the borders of Nottinghamshire and Derbyshire, have been recently explored, and the relics thereby brought to light prove that man lived in the hunter-stage of civilisation in the valley of the Trent and its tributaries, along with the mammoth, woolly rhinoceros, cave-hyena, lion and reindeer, and that he was capable of progress. In the lowest stratum in the caves, says Professor Dawkins, implements are found of the rudest kind and roughest form, made of quartzite pebbles from the neighbourhood. In the middle stratum implements of flint appear mingled with the others; but in the uppermost stratum the tools and implements are of flint, and of the best kind. Among these are bone needles and other appliances of bone and horn, on one of which is rudely engraved a figure of a horse. ‘This sequence,’ remarks the Professor, ‘establishes the fact, that even in the palæolithic age the hunters of reindeer, horse, mammoth, and other creatures were progressive, and that the cave-dwellers of the pleistocene age are to be looked upon from the same point of view as mankind at the present time, as “one man always living and incessantly learning.”’ If Professor Dawkins is right in his conjecture, the cave-dwellers of the very remote period which he describes were somewhat like the Eskimos of the present day.

To this we may add the fact, that rude stone implements have been found in the ‘glacial drift’ in New Jersey, United States, and that some geologists regard this as proof that man lived on the earth during that far-back, dreary, and cold glacial period.

In the course of the admirable surveys of their wide-spread territory carried on by authority of the United States government, discovery has been made of strange and interesting remains of habitations, implements, and pottery of a long-departed and forgotten people, who once occupied the region about the head-waters of the San Juan. Photographers and geologists among the surveying parties have by means of pictures, drawings, and descriptions produced a Report, which will in due time be published at Washington. Meanwhile models of the ancient ruins have been constructed in plaster, and compared with the dwellings of certain Indian tribes in New Mexico and Arizona; and these latter, with allowance for contact with Europeans, are at once recognised as bearing traces of the dwellings of the forgotten people. ‘Forgotten,’ says an American contemporary, ‘because the builders of the modern structures are as ignorant of the ancient builders as we are ourselves.’

A correspondent suggests that the ‘stencils’ produced by Edison’s Electric Pen might be used as communications for blind people, whose sensitive fingers would, he thinks, feel out the meaning of the very slight roughness of the surface of the paper occasioned by the punctures. Why does he not try the experiment? Meanwhile we mention that a naturalist in New York has produced a Catalogue of Diatomaceæ by means of the Electric Pen, and published it in quarto form for private distribution.

Another correspondent informs us that the horse-shoe described in the Month (July 1877) as brought into use in Philadelphia with satisfactory results, was invented in England in 1870 by Mr C. J. Carr. A statement printed in 1874 sets forth that the shoe is made of malleable iron in such a way ‘as to allow of the natural growth of the frog while completely shielding the foot. On the face of the shoe is a hollow semi-circular cavity, which is filled with a pad of hemp and tar; and as no calkins or spikes are required, one of the dangers incident to roughing is entirely obviated.’ We wish success to any one who will persevere in applying common-sense and kindness to the shoeing of horses.

The Japan Daily Herald of 31st January states that when the telephone was brought under the notice of the Japanese government, Mr Ito, the (native) Minister of Public Works, at once ordered experiments to be made. These were carried out by Mr Gilbert, Telegraph Superintendent-in-chief to the Japanese government, and formerly of Edinburgh. The experiments were so satisfactory that they were followed by the establishment of telephonic communication between the police stations in the metropolis and between the Emperor’s palace and the various government departments. When the Public Works Department and the palace were first put in telephonic union, the Emperor and Empress were present, and expressed great surprise at the result. The English newspaper, in recording this fact, adds, ‘As well their Majesties might;’ and it proceeds to speculate whether the Chinese, who have opposed telegraphs and railways, will ‘give ear to the telephone.’ No great expectation appears to be entertained that the Chinese will do anything of the kind.