In our own navy, a new form of machine-gun will be probably supplied to the various ships, more especially for boat-service. For some time the Nordenfelt gun has been a service-fitting; but it is now proposed to introduce a Nordenfelt of larger calibre, which will fire explosive shells instead of solid bullets. From recent experiments at Portsmouth, the new weapon seems to be wonderfully efficient. For instance, a gun firing a shell weighing only two pounds was able to send its projectile through a solid steel plate two inches thick at a range of three hundred yards. It was shown, too, that a far larger Nordenfelt, a six-pounder, could be fired from a boat without straining it. These destructive weapons can be fired so rapidly as to deliver from eighteen to twenty-five shots per minute.
The Telegraphist newspaper publishes an account of what must be regarded as a truly marvellous triumph of electrical communication, before which Puck’s proposal to ‘put a girdle round the earth in forty minutes’ seems to be quite a second-rate achievement. A correspondent of the paper in question visited the office of the Indo-European Telegraph Company by invitation, in order to note how good signalling could be maintained over thousands of miles of wire. First, a few words of conversation were exchanged with the telegraphist of a German town. The wire was next connected with Odessa, and next with the Persian capital (Teheran). In a few more minutes the experimenters in London were talking with the clerk in charge at Kurrachee; next they had a chat with a gentleman at Agra; and as a final triumph of science, the line was made direct between London and Calcutta, a distance of seven thousand miles. It is said that the signals were excellent, and the speed attained about thirteen words per minute.
In a recent lecture upon gas-lighting, Mr Thomas Fletcher pointed out that blackened ceilings and darkened picture-frames are not due to smoke from the gas-burners, but are caused by floating particles of dust being caught in the flame and thrown against the ceiling. It is easily proved, by holding a glass tumbler for a few seconds over a flame, that water is one of the products of combustion of gas. This water condenses upon a cold ceiling when the gas in a room is first lighted, so that the burnt particles of dust readily adhere to the flat surface. The servant who lights the gas on a dark morning before she proceeds to sweep and dust the room does practically all the smoking of the ceiling that takes place.
That unfortunate commercial experiment, but marvellous triumph of engineering skill, the Great Eastern steamship, will shortly proceed to Gibraltar to take up her position in the harbour as a coal-hulk. The gigantic paddles with their engines will be removed, leaving the screw propeller only to carry the ship to her last berth. The Admiralty authorities look with much favour upon the scheme, for the immense ship will supersede a number of small coal-hulks which now encumber the harbour, and are a source of much inconvenience to other vessels. We are glad that a use has been found for the unwieldy vessel, whose only serviceable work has been as the layer of the first Atlantic cables. She was far too big to be profitably worked, and has for many years been lying idle. Her new vocation, although of a lowly kind, is at anyrate better than pauperism.
A new motor, called a ‘Triple Thermic Motor,’ has, it is said, been in use in New York for the past seven months driving a sixty horse-power engine. Heat is generated by a fifteen horse-power boiler, and the steam thus raised is carried to a receptacle containing carbon disulphide, which passes into vapour at one hundred and eighteen degrees Fahrenheit. An engineer, in reporting upon this new contrivance, says that the fifteen horse-power boiler with very little fire under it generates steam, which operates the motor, which in turn runs the sixty horse-power engine. These seem to be all the particulars published; and it would be interesting to have details of the motor, if it be really as successful as reported. There are one or two difficulties to surmount in the employment of carbon disulphide. It has a most disagreeable and penetrating odour; its vapour is highly inflammable; and lastly, it is by no means cheap.
Some interesting particulars of the American lead-pencil trade have recently been published. With the improved machinery now in use, it is possible for ten men to turn out four thousand pencils a day. The cedar comes from Florida in slabs cut to pencil-length. Four parallel grooves are sawn in each little slab, each groove being destined to hold the lead, or rather graphite. The so-called leads are kept in hot glue, and after being inserted in the grooves, are covered over with a thin slab of cedar, also glued; then the whole is passed through a moulding-machine, and comes out at the other side in the form of four finished pencils. The graphite is mixed with a variable amount of white clay—the greater the proportion of clay the harder the pencil—and is ground with moisture into a paste. The paste is pressed into dies, and is baked at a high temperature.
The recent outbreak of smallpox in London reminds us that we have not yet succeeded in stamping out this loathsome disease, although the practice of vaccination has checked it to a wonderful extent. Anti-vaccination agitators are very fond of pointing to the circumstance that many persons who have been apparently successfully vaccinated in childhood are in after-years attacked with smallpox. This is perfectly true; and statistics are available which show that in the years between 1871 and 1881 nearly eighteen thousand such cases were treated in the London hospitals. But the popular agitator abstains from pointing out that in ninety per cent. of these cases the sufferers were above ten years of age. These figures prove, in fact, what has been long ago acknowledged, that vaccination does not afford permanent protection. When a child reaches adult age, revaccination should take place. In our smallpox hospitals, the nurses and attendants enjoy complete immunity from infection by taking care to adopt this precaution; and all persons, for the general good of the community at large, would do well to submit to the trifling inconvenience which the operation entails.
The Isthmus of Corinth Canal, a scheme which was promoted originally so far back as the time of the emperor Nero, is now almost an accomplished fact. The dredging operations at the approaches to the canal proceed very rapidly, for about five thousand cubic metres of soil and sand are removed every twenty-four hours. There are large numbers of workmen employed also on the central portions of the channel, and they have the help of railway and plant for the conveyance of material. A new town, called Isthmia, has sprung into being, and it contains some two hundred houses and stores.
‘The Rivers Congo and Niger viewed as Entrances for the Introduction of Civilisation into Mid-Africa,’ was the title of a paper lately read before the Society of Arts by Mr R. Capper, Lloyd’s agent for the district of the Congo. The lecturer stated that within the past five years, the western African trade has quadrupled in value. Twelve years ago there were but four English houses, one French, and one Dutch, trading up the Congo. There are now upon the river’s banks forty-nine European factories, and the imports and exports are valued at two millions sterling. Mr Capper pointed out that the great value of these rivers lies in the possibility of connecting them with future railways. Such railways could be easily laid, for the interior of Africa is one vast tableland. A railway across the Desert of Sahara would turn a perilous journey of four months into one of twenty-four hours. By such means the interior slave-trade would be annihilated.
Boring in the earth for water is an operation often attended by great uncertainty. Some few years ago in the heart of London a firm of brewers bored to a depth of several hundred yards without tapping the precious fluid, and the expensive well had to be abandoned. Quite recently, at Burton-on-Trent a similar failure occurred upon a far smaller scale. When the operators had pierced to a depth of one hundred and seventy-six feet without finding water, they called in the advice of some experienced artesian-well engineers, who recommended the abandonment of the works, and the commencement of a fresh bore upon a site which they selected two hundred yards away. At a depth of only one hundred and fourteen feet, a copious supply of water was found, yielding, in fact, between five and six thousand gallons per hour. It is remarkable that the sites of both bores were at the same level.