OCCASIONAL NOTES.
THE RECENT EARTHQUAKE IN ENGLAND.
During the past few years, there have been recorded, unhappily, an unusual number of earthquakes in various parts of the world; and many thousands of lives have been lost by those terrible convulsions of nature. Inhabitants of Britain, although constant in their complaints of fog, inclement seasons, and other meteorological inconveniences, have hitherto congratulated themselves upon living in a country which is exempt from volcanic phenomena, and in which earthquakes seemed to be things of a past era. These comfortable reflections were suddenly dispelled on the morning of the 22d of April, when over a large tract of country in Southern England a shock of great severity occurred. In the town of Colchester, and many villages eastward of it, the destruction of houses was very great. Many were entirely unroofed; and in some villages, as the writer can testify from personal observation, it was the exception to note a dwelling in which the chimney-stacks had not been demolished. Providentially, no lives were lost, although several narrow escapes have been recorded. The damage is estimated to amount to several thousand pounds, and unfortunately the sufferers are as a rule very poor cottagers, who are unable to bear the expense of the necessary repairs. For their relief, a subscription has been set on foot under the auspices of the Lord Mayor, and there is little doubt that sufficient money will be readily forthcoming for their needs.
The occurrence of such a rare phenomenon in the British Isles—not quite so rare, by the way, as some people imagine, for nearly three hundred shocks have been actually recorded—has caused an immense amount of earthquake lore to be unearthed and published in the various newspapers. From Iron we have an interesting account of the way in which luminous paint is utilised in connection with earthquake alarms in countries where such visitations are prevalent. We are informed that large consignments of the paint are sent to such places, and that the material is employed in the following manner. Small metallic plates covered with the paint are fixed on the doorposts of the different rooms, so that at the first alarm—and happily there is often a premonitory warning of something more serious to follow—the inmates of the houses can readily find their way outside. In Manila, the paint is laid in patches about the staircases, door-handles, and various points of egress. A light which gives off neither fire nor heat is of the greatest value in such situations, where any other form of light would be apt to add its quota of disaster to the dangers to life, already too prominent.
IMPROVED ELECTRIC LIGHTING FOR SHIPS.
Mr J. D. F. Andrews, Woodside Electric Works, Glasgow, has lighted with electricity, after a new fashion, the North German Lloyd S.S. Ems. The system, which includes over three hundred and twenty incandescent lamps and a masthead arc lamp, presents some features of a novel and important character. In the case of the small lights, Swan’s lamps and Siemen’s machines are employed. The wires are all completely hidden, but they are nevertheless arranged in such a way that they can be easily reached when necessary. For these lamps there is provided a new style of holder, which is at once simple and efficient. Each lamp has its own switch, which is entirely of metal; and it is provided with a lead-wire, which fuses in the event of the current being too strong. In the case of every set of about twenty lamps there is another switch, so that the lights can be turned on and off in groups as well as individually; and another lead-wire, so that the leading wires may be protected from too strong a current. The whole system is such as to preclude the possibility of fire. Duplicate machines are fitted up to guard against any breakdown, and either of them can be started or stopped without interfering with the engine which drives them. The masthead arc lamp, of which Mr Andrews is the inventor, is here brought into requisition for the first time. It has about five thousand candle-power concentrated in a single beam of light, that can be moved in any direction forward of the ship. In construction it is extremely simple, consisting merely of a cylinder and piston, the former being an electrical coil of wire. The illuminating power of the lamp is so great that by means of it an object half a mile away can be clearly distinguished by the naked eye on a dark night.
DUTCH RUSH.
‘Many years ago,’ says Mr W. Mathieu Williams, in the Gentleman’s Magazine for March, ‘when the electrotype process was a novelty, I devoted a considerable amount of time and attention to the reproduction of medallions and other plaster-casts in copper by electro deposition. This brought me in contact with many of those worthy and industrious immigrants from Bagni di Lucca (between Lucca and Pisa), who form a large section of the Italian colony of Leather Lane and its surroundings. These Lucchesi are the image-makers and image-sellers, and general workers in plaster of Paris. Among other useful lessons I learned from them was the use of the so-called Dutch rushes, which are the dried stems of one of the most abundant species of the equisetum (Equisetum hyemale) or “horse-tail,” which grows on wet ground in this country and Holland. It is well known to practical agriculturists as a tell-tale, indicating want of drainage.
‘Plaster-casts are made by pouring plaster of Paris, mixed to a creamy consistence with water, into a mould made of many pieces, which pieces are again held together in an outer or “case-mould” of two or three pieces. When the mould is removed piece by piece, fine ridges stand up on the cast where the plaster has flowed between these pieces. These ridges are removed by rubbing them obliquely with the surface of the stem of the dried equisetum. It cuts away the plaster as rapidly as a file, but without leaving any visible file-marks. The surface left is much smoother than from fine emery or glass-paper, and the rush does not clog nearly so fast as the paper.
‘In order to find the explanation of this, I carefully burned some small pieces of the equisetum stem, mounted the unbroken ash on microscope slides with Canada balsam, and examined its structure. This displayed a flinty cuticle, a scale-armour made up of plates of silica, each plate interlocking with its neighbours by means of beautifully regular angular teeth, forming myriads of microscopic saw-blades, which become loosened from each other and crumpled up in drying, and thus present their teeth obliquely to the surface. These teeth supply the image-maker with a file of exquisite fineness, and harder than the best Sheffield steel. Their comparative freedom from clogging I think must be due to their loose aggregation while held by the dried and shrivelled woody tissue of the sub-cuticle.