Chapter XVI (2)

Lloyd’s agent at Athens has recently reported some information as to the progress of the canal which is to cut the Isthmus of Corinth. Out of a total of thirteen million cubic yards of earth which must be dug out before the canal is completed, nearly three millions have been removed. The canal is to have a surface width of twenty-four yards, except at the entrances, which will be widened to between fifty and sixty yards. One thousand men are at present employed upon the works, which, at the present rate of progress, should be completed in five years.

The Austrian government offer a prize of one thousand ducats (nearly five hundred pounds) for the discovery of a system of working coal in fiery mines without shot-firing. The method must not be more expensive than that of ordinary blasting. It must not be capable of igniting fire-damp or coal-dust, and it must not leave any injurious products behind it. These are the chief conditions.

An improved method of etching metallic surfaces has been invented by Mr A. Piper of Wolverhampton. The metal surface is first of all coated with gold, silver, nickle, brass, or any other metal desired, in the ordinary electro-plating bath. The design is then drawn upon it in some resinous or other acid-resisting medium, and the metal is immersed in an acid, which eats away the coating, and at the same time produces a dead or frosted appearance upon the exposed metal beneath. The resinous drawing is now removed by any suitable medium which will dissolve it, leaving the design in relief upon a frosted ground. If desired, the operation can be reversed by leaving a groundwork of plated metal, while the design is bitten out by the acid.

A new stationary buffer-stop for railway stations and sidings was recently described in a paper read before the Institution of Mechanical Engineers by Mr A. Langley of Derby. This buffer-stop consists of two hydraulic cylinders fitted with pistons. The piston rods carry in front buffer-heads to meet those on the locomotive. There are also projecting rods behind the cylinders connected by chains with counterweights, to return the pistons after pressure to their former position. The pistons have a stroke of four feet; and it is calculated that this amount of depression would effectually stop a train without jerk or damage even if it were moving at the rate of eight miles an hour.

Gases inclosed in iron cylinders under enormous pressure are now used in various branches of science and art, and are supplied commercially by many firms in various countries. The gases most commonly used are hydrogen and oxygen—for the lime-light—carbon dioxide, and nitrous oxide—this last being much employed as an anæsthetic by dentists. Hitherto, there has been much difficulty in controlling the outrush of gas from these cylinders, for the internal pressure often amounts to six hundred pounds on the square inch. By the aid of a new regulator, invented by Messrs Oakley and Beard of London, this difficulty is at once obviated. The regulator consists of a small india-rubber bellows inclosed in a brass box, which screws upon the nozzle of the gas cylinder. By an ingenious device, as the bellows top rises with the pressure of the gas, a screw valve descends upon the opening in the cylinder. In this way the user of the gas can regulate the outflow to his requirements. We understand that it is in contemplation to adapt the same principle to ordinary gas consumption in houses, so that the supply may always be adjusted to the number of burners in actual use.

Habitual drinkers of aërated beverages were some time ago startled by the report that the original source of the water used in the manufacture did not much trouble the attention of the vendors, and that micro organisms in fabulous numbers might find their way to the consumers of these apparently innocent fluids. According to Dr T. Leone’s researches, aërated waters are peculiarly safe from such contamination. Taking a typically pure potable water, he tried how many micro organisms could be developed in it in a given time. In five days the water contained immense numbers of organisms. But when charged with carbonic dioxide, as all aërated waters must be to give them their effervescent quality, the number of living creatures was at once diminished. Water so charged contained at the end of fifteen days only a mere trifle of the original organisms. Dr Leone therefore concludes that the longer aërated waters are kept, the less chance is there of bacterial contamination.

The greatest living authority on bacteria, M. Pasteur, has by recent experiments proved that water containing only two per cent. of concentrated sulphuric acid possesses the property of destroying these organisms. He recommends that this acidulated water should be used as a disinfectant for floors of stables, mangers, courtyards, cattle-sheds, &c. The compound has certainly the merit of extreme cheapness, for about twelve gallons could be prepared at a cost of twopence. We may mention that M. Pasteur’s inoculations for hydrophobia have met with unlooked-for success. He recently told the Paris Academy of Sciences that out of three hundred and twenty-five cases of inoculation for this terrible disease, only one had proved a failure, and that one he attributed to delay. It is suggested that an international hospital should be established for the reception of patients from every country.

The all-seeing microscope has very often played an important part as an accusing witness, more especially in the identification of blood-stains. Recently in Illinois the same detective agent was instrumental in hanging a murderer; but the method of conviction was novel. Here is the case: A. had been found murdered while sleeping on a pile of sawdust in a certain icehouse, which we will call No. 1. B. was suspected of the crime because particles of sawdust were found on his clothing and on his boots. He accounted for this by pleading that he had been sleeping in another icehouse (No. 2) which was far away; and declared that he had not been near the No. 1 house. It was proved that icehouse No. 1 contained _pine_ sawdust, and house No. 2 hardwood sawdust only. The microscope showed that the clothes and boots had attached to them particles of the former only. The man was convicted and executed.

Professor Vogel has lately brought forward the curious fact that the generation of alkaloids in plants is dependent upon sunlight. The hemlock plant which yields coniine in Southern Europe contains none in Scotland. Again, the tropical cinchonas, from which quinine is obtained, will yield very little of that valuable product if cultivated in our weakly lighted hothouses. Professor Vogel has examined many specimens of the plant from various conservatories, and has been quite unable to obtain the characteristic reaction of quinine, although the method of testing is a delicate one, and sensitive to minute quantities of the alkaloid. It is curious to observe that although sunlight seems so necessary to the formation of quinine in the living plant, it acts most injuriously upon the alkaloid in the stripped bark. In the latter case, the quinine is decomposed by it, and assumes the form of a dark-coloured resin. Because of this, in the manufacture of quinine, the bark is always dried in the dark.

The recent severe weather must have led many a half-frozen traveller to wonder if our railway and tramway Companies will ever hit upon some method of heating public conveyances. With a steam-engine as a necessary adjunct, it would seem to the disinterested inquirer that a method of warming by pipes fed from the ‘exhaust’ would be a comparatively easy way of managing the business, and would at the same time save much labour in doing away with the filling and distribution of inefficient foot-warmers. In Chicago, a new method of heating tramcars is being tried, and it promises well. The apparatus, which is placed under the floor of the car, consists of a brass cylinder filled with coal-oil, which, under pressure of a strong spring, is forced into a small super-heater, where it becomes vaporised. This oil-gas is ignited in a fire-clay combustion chamber, and although there is no flame, the fire-clay is brought to a white heat. The outer air passing over this hot box becomes well warmed, and a constant stream of fresh, warm air is assured to the passengers. The only visible evidence of the stove is a grating in the floor of the car through which the hot air rises. When will our tramway Companies consent to a small reduction in their high dividends, to afford their patrons similar comfort?

The use of wood pavements in Sydney has been very strongly condemned by a Committee appointed by the Legislative Assembly of New South Wales to inquire into the subject. It had been alleged that these wood pavements exerted a deleterious influence on the health of persons living in their proximity, and the conclusions arrived at by the Committee would seem to justify these allegations. Analysis showed that the blocks in actual use had absorbed a vast amount of organic matter, even though they had only been laid down a comparatively short time. It was evident, too, that complete impregnation of the wood was only a matter of time. In the words of the Report: ‘So far as the careful researches of your Board go, the porous, absorbent, and destructible nature of wood must, in their opinion, be declared to be irremediable by any process at present known; nor, were any such process discovered, would it be effectual unless it were supplemented by another which should prevent fraying of the fibre.’ It should be noted that this strong condemnation is applied to the _hard_ wood-blocks used for the purpose of paving in Sydney, and not to the soft wood used here at home. These latter are so thoroughly impregnated with tar, that it is difficult to imagine that room could be found for anything else, organic or otherwise.

The cable tramway which is situated on the historic hill at Highgate, London, has worked without hindrance during the recent frost and snow. This is due to the fact that the working parts are underground. But of late a new use has been made of the system. Heavy vehicles even with six horses attached could not be moved up the hill during the recent frosts. Many of them were therefore fastened to the tramcars, and were pulled up the steep incline—one in eleven—at the rate of six miles an hour.

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.

A NEW BOILER-FEEDER.

The problem of feeding boilers has yet to be solved, no method yet introduced having by its intrinsic merits superseded all others. At the present time, injectors or donkey-engines are usually employed—the former being an ingenious apparatus which forces the feed-water into the boiler by the rush of steam through a narrow orifice; the latter differing in no way from an ordinary pumping-engine, and usually deriving its power from the boiler itself. Both these systems of feeding require constant supervision; and it is to obviate the necessity of continued attention and the risk resulting from carelessness, that boiler-feeders automatic in action have been designed. So far, their application has not been extensive; but a recent improved design, patented as ‘Mayhew’s Automatic Boiler-feeder,’ bids fair to push its way even in these times of depressed trade, when boiler-owners not unnaturally hesitate to incur any outlay, however slight, which a rearrangement of the boiler-feed necessarily entails. The apparatus consists essentially of two vessels—the upper of copper, the lower of cast-iron. An ingenious valve-arrangement connects the former with the boiler, whilst the latter is connected with the supply of feed-water. When the water in the boiler falls below a certain level, the end of the pipe connected with the upper vessel becomes uncovered, and the steam being free to enter it, operates on the valves, thereby admitting a charge of water to the boiler from the copper vessel. A vacuum is formed in the copper vessel, which now recharges itself from the one beneath, ready for another operation. As many as five charges a minute can thus be obtained. Should the apparatus, from any cause, fail to work, and the water fall too low, a fusible plug melts and sounds an alarm whistle. It is satisfactory to note that an ingenious straining arrangement works well for feeding with dirty water—the great difficulty in all apparatus of this class, owing to the valves becoming choked. The feeder may be regarded as safely beyond the mere experimental stage, a large number already being in operation in different works throughout the country, and with results satisfactory in every respect.

SHOT-FIRING IN COAL-MINES.

A correspondent thus writes: ‘In your article on “Shot-firing in Coal-mines” you speak of the dangerous operation of tamping or plugging the shot-hole with brick or coal dust rammed hard. It must indeed be a dangerous operation; but cannot the hole be as effectually plugged without any danger at all? It is usual, after charging a rocket, to drive in dry clay upon the top of the fuse, to prevent its blowing through; but a layer of wet plaster of Paris poured in and allowed to set, dries harder than the clay, and obviates all danger from concussion or grit. Cannot the shot-hole be in like manner plugged? Plaster of Paris (gypsum or sulphate of lime) expands, not shrinks, when combined with water, so that it fills accurately every part of the bore. If the hole were slightly conical, the smaller end outwards, or made with an internal flange, the plaster would offer more resistance than the clay.’

PARTED.

The silver brooks will miss thee,
The breeze that used to kiss thee,
And ruffle with a soft caress thy curls of sunny hair;
When the early dewdrops glisten
On the roses, they will listen
For thy step upon the garden walk, thy laughter in the air.

The meadows gay with flowers,
The summer’s leafy bowers,
Will know thy joyous smile no more; the woodlands stand forlorn;
I hear the soft complaining
Of birds, from mirth refraining.
That greeted with their carols sweet thy waking every morn.

Poor mother! hush thy weeping
Above thy darling sleeping,
Nor fret with aught of earthly grief the stillness where he lies,
Flowers in his little fingers,
Where the rosy flush still lingers,
For the angels are his playmates on the plains of Paradise.

J. I. L.

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