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ago the old oil light was superseded by the magneto-electric light,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.