The annual report on the great trigonometrical survey of India contains particulars which shew that surveying in India is by no means holiday pastime. Colonel Montgomerie, who has just retired after twenty-five years' service, was engaged during nine of those years in a survey of the dominions of the Maharaja of Kashmir, comprising about 77,000 square miles. Within this extensive area rise stupendous mountain ranges and peaks, the highest of which is more than 28,000 feet, and the Indus, Jhelum, Kishanganga, and other great rivers, flow through the valleys. To fix the position of heights and places in such a country requires a combination of courage, skill, and endurance rarely to be met with, but which happily for geographical science has been forthcoming ever since the Indian survey was commenced. The annual reports contain many accounts of adventurous journeys, and hazardous exploits which few readers would think of looking for among the dry details of a scientific triangulation. Sometimes on resuming work after the rainy season, the 'rays' or lanes which had been cut through the forest to clear a way for taking distant sights, would be found so choked by the shoots from tree-stumps and young bamboos which had grown to an 'astonishing height,' that more than thirty miles of such rays had to be cleared over again before the work could proceed. On extending the survey into Burmah it was only by cutting tracks through the dense forest that communications could be effected from station to station, and whenever an existing road could be made available it was regarded as a luxury. At Kamákabo it became necessary to carry the great theodolite to the top of a rocky hill: the sharp projecting rocks 'jutted out in every direction,' and as they could not be removed, ladders were stretched from rock to rock, and thus a most perilous ascent and descent was accomplished. The labour and risk may be judged of from the fact that the theodolite weighed more than six hundred pounds, and we can appreciate the satisfaction with which the observer wrote in his journal, 'it was a day of rejoicing when the instrument was brought down in safety.' At times a region of sand-hills was traversed where vision was not obstructed, but where not more than three wells of drinkable water were found in a distance of seventy miles. And once the observer waded through a mile of mud and water under a burning sun to an old lighthouse whence it was essential to take angles to fix the position of the new one five miles distant. A consequence of this exploit was an attack of malarious fever.
It seems likely that trigonometrical surveying may be carried on with less difficulty in future; for an Italian officer of engineers, Lieutenant Manzi, has proved that the triangulations can be photographed. It is possible to construct a camera geometrically arranged, and if the rays of light converging from distant points of view are intercepted, and marked on a diaphragm, it is evident that the angular readings obtained to such points would be identical in their bearings with the objects themselves. By such a camera, negative views of inaccessible ground can be faithfully taken, and the angles can be either plotted or calculated. Photography thus offers itself as a means whereby a difficult mountain country can be surveyed without risk, while for purposes of military recognisance its advantages are obvious.
For some time past attention has been directed towards steel-wire cables; and experiments recently made in Portsmouth Dockyard have clearly demonstrated their superiority over hemp and iron. Steel, as is well known, is more and more used in the building of ships, and, because of its tenacity and lightness, in their rigging; and now it seems likely to supersede the unwieldy hawsers and chain cables everywhere in use. With a chain the safety of the ship depends on the weakest welding; and when a single link parts, either from inherent defect or from a sudden jerk, everything parts, and the vessel drifts. A wire cable, on the contrary, gives notice, so to speak, of an approach to the breaking point. First one strand, then another, gives way, and still the cable holds, and it may happen that it will hold long enough to save the ship. Now that experiment has proved that a steel-wire cable is as flexible as the best hemp, that it is three times as strong, and does not cost more, the change from one to the other may be made with confidence. Another advantage is the lightness, for by making use of steel, about two-thirds of the usual weight of the cable is got rid of. Evidence of the strength is seen in the fact that a three-inch steel hawser did not break until the strain exceeded twenty-two tons, and that a strain of more than a hundred tons was required to break the six-inch.
Lieutenant Totten of the United States Army, in writing about explosives and big guns, discusses carefully the question as to the best kind of explosive for actual service; that which will expend its entire force in driving out the projectile. With the large-grained gunpowder now in use about half of the charge is wasted, while gun-cotton and dynamite exert an injurious strain upon the gun. As a way out of the difficulty, he recommends a 'compensating powder,' each grain of which contains a core of gun-cotton, and he points out that forty pounds of this powder would be sixty pounds stronger than a hundred-pound charge of gunpowder. The explanation is that by the time forty pounds of the hundred are burned, the shot has left the gun; consequently, sixty pounds are of no help to the shot. But if the forty pounds contain fifteen pounds of gun-cotton, then this cotton, when fired, acts on the already moving shot under the most favourable circumstances as a pure accelerator, and does not injure the gun. In this way, writes Lieutenant Totten, 'we eliminate the great waste of the one, curb the straining action of both, and obtain a true artillery powder, lighter, and four and a half times more effective, charge for charge, than our best gunpowder.'
An address 'On Light in some of its Relations to Disease,' delivered to the Albany Institute (State of New York) by Dr Stevens, sets forth views and facts which are worth consideration. Light, as we know, is on the whole beneficial; but may there not be cases in which it is harmful when passing through the transparent media of the human eye? Dr Stevens is clearly of opinion that many nervous diseases are aggravated if not produced by defective vision. The strain on the muscles of the eye, when long continued, sets up an irritability which tells injuriously on the nervous system, and neuralgic affections. St Vitus's dance and severe periodical headaches are the consequence. Rectify the imperfection of the sight, says Dr Stevens, by proper spectacles, and the nervous disease will be either mitigated or cured. It is of no use to buy glasses at hazard because they seem to suit the eye; for none but a scientific oculist can really decide, after careful experiment, on what is proper. In many cases the focus of the two eyes is not the same, and each must have its proper glass. Professor Donders of Utrecht was the first to point out that the so-called 'cylindrical glasses' were generally the most efficient; and since then 'the science of correcting anomalous refractions of the eye has been brought to a perfection which is truly wonderful.'
Dr Poumeau of Guadeloupe has published a series of tables, based on the changes of the moon, by which, as he believes, it is possible to tell the sex of a child before birth. He intends to draw up similar tables for the use of horse and cattle breeders; and if any one should test his calculations by observation, the doctor would like to be informed of the result.
The Journal of the Chemical Society contains an account by Mr Hight, of the Indian Forest Department, of experiments made with a view to ascertain the practical nature of a proposed method of determining the mineral strength of soils by means of water-culture. It is explained that the usual object of water-culture experiments is to find what particular salts are congenial or necessary to the growth of any particular plant. When a plant is grown in an artificially prepared solution, so that it can obtain its nourishment solely from the salts contained in that solution, the exact effect of any salt upon the growth of the plant can be easily observed by adding that salt to, or abstracting it from the solution. In carrying out this method, specimens of soil were taken from five different forests in India; solutions of these specimens were made; seedlings of Acacia arabica were, with proper precautions, placed in each, and the results of growth, such as increase in weight, number of leaves, and length of roots, were carefully noted. These results are published in a numerical table, and allowing for the difficulties of a preliminary experiment, may be regarded as satisfactory.
The question is frequently asked—Why is there no School of Forestry in England, while in almost all other countries of Europe schools of forest science are either established by the government, or are associated with a university or a polytechnic institution? Sir Joseph Hooker, President of the Royal Society, and Director of the Royal Gardens, Kew, says in one of his reports, that the subject is so neglected in this country, that when our government are in want of a forest inspector for India, they have first to send him to France or Germany to learn the theory and practice of taking care of a forest. On the continent, as Sir Joseph remarks, 'forestry holds a distinguished place among the branches of a liberal education. In the estimation of an average Briton, forests are of infinitely less importance than the game they shelter, and it is not long since the wanton destruction of a fine young tree was considered a venial offence compared with the snaring of a pheasant or rabbit. Wherever the English rule extends, with the exception of India, the same apathy, or at least inaction, prevails. In South Africa, according to the colonial botanist's report, millions of acres have been made desert, and more are being made desert annually, through the destruction of the indigenous forests; in Demarara the useful timber trees have all been removed from accessible regions, and no care or thought is given to planting others; from Trinidad we have the same story; in New Zealand there is not now a good Kauri pine to be found near the coast, and I believe that the annals of almost every English colony would repeat the tale of wilful wanton waste and improvidence. On the other hand in France, Germany, Switzerland, Austria, and Russia, the forests and waste lands are the subjects of devoted attention on the part of the government, and colleges, provided with a complete staff of accomplished professors, train youths of good birth and education to the duties of state foresters. Nor, in the case of France, is this practice confined to the mother country: the Algerian forests are worked with scrupulous solicitude, and the collections of vegetable produce from the French colonies in the permanent museum at Paris contain specimens which abundantly testify that their forests are all diligently explored.'
This is a long quotation; but it is justified by the importance of the subject, and it is quite clear that we cannot go on much longer without a School of Forestry. Diligent students can hardly fail to be forthcoming, and when once they shall have proved themselves efficient inspectors, the question of 'good' birth may be left to take care of itself.