(ENIUS, in the engineer, is the perfection of common sense. It is his duty to deal with material fact. His education therefore involves, first, the knowledge of those simple and unvarying laws which regulate stability and motion on the surface of our planet, and secondly, a full and exact acquaintance with all those details of fact Iwith which he has to deal. His whole lore is the outcome of experience. He may, indeed, as he advances in his career, learn how to express in compact mathematical formulæ the laws under which he acts. He will accumulate tables as to the strength and weight of the materials which he not only uses but manufactures. But for every formula, for every table, he has to recur to the guidance of experience, direct or traditional. So long as the mechanician sought to work deductively, he did nothing. When he entered on the path of induction, he commenced a progress towards the dominion of the world.

This view of the position of the engineer, as naturæ minister et interpres, explains how it is that men almost utterly destitute of what we regard as educational advantages have exerted more influence on human welfare and material progress than the greatest ministers, the most consummate generals, and the most saintly ecclesiastics. What chiefly remains, at the present moment, to bear witness to the colossal proportions of the genius of Napoleon? His roads, and other public works-for in framing his code he had to seek the aid of experts. What is the most permanent memorial of that great Churchman who was once said to be able to―

With his very bulk

Take up the rays of the beneficial sun And keep it from the Earth? The tower and vaulted roof of Christ Church. But neither Napoleon nor Wolsey has produced, in all the time that has elapsed since their names counted for mighty forces in the world, the tithe or the hundredth part of the effect that has followed on the converse held with nature by a Northumbrian labourer, who could not read when he was eighteen years old, who commenced life on the wages of twopence a day, and who declared himself a rich man when at last he had achieved the saving of a guinea.

One reason of the success of Stephenson was his lack of book education. Had he once been placed in the conventional groove he might never have left it. He was brought face to face with nature. In the works of her hand, plant, and tree, and bird, he took delight. But it was on the display of her physical forces that his mind. chiefly dwelt. The power of steam was in its cradle when Stephenson first took to tending a colliery engine. Rocking that cradle, he became day by day familiar with the wants and with the capabilities of the infant giant. Step by step he learned his art of the mechanic, from the daily effort to supply the need, and cure the defects, of the machinery he had to drive. If we trace his course from day to day, we shall see little at which to wonder, except the pith, the perseverance, and the patient study of the man. Yet between his first appointment to drive the rude self-moving engine at Killingworth and the moment when the Rocket astonished the world at

Warrington, lay the springs of a physical revolution more mighty than any that had been accomplished since man first learned to kindle fire.

Educated England, in spite of School Boards and of competitive examinations, and in spite of the more practical benefits to be derived from some of her most broadly educated children, has not yet learned to look upon the art of the engineer as other than a mystery. People in high places have not yet discovered that the useful knowledge of the engineer is the exhaustive knowledge of facts. As persons entirely ignorant of machinery are wont to attribute the most wonderful effects to the action of a 'spring,' so are most folk in the habit of thinking that it is to the original genius of some very lofty mind that we must look for the solution, per saltum, of more than one of those vexed mechanical or chemical questions, the proper treatment of which, as I have before now attempted to show, is becoming more and more an element of social welfare-even of social existence.

A remarkable instance of the fail. ure of the English public, even regarding the more highly cultivated strata of society, and the amateur followers of arts, to appreciate this character of the functions of the true engineer, is to be found in the recent invitation to inventors to produce some large and comprehensive scheme of a national character' for the supply of water to the population of England. Of the patriotic care and wise forethought that first put that question in direct form, it would be difficult to speak in terms of too high admiration. But the defective part of the case is the need that such a question should be put, and the fact that the true and only reply should have failed for a single week to be forthcoming. It may be of service

to the public at large, to show how certainly and exclusively the reply to the Prince of Wales's enquiry is to be framed.

The clue to that answer is to be found in the preceding remarks. Let us suppose that the question were put, not to a scientific or quasiscientific body of any nation, but to an individual who was expected to furnish a definite reply. Such an individual, in almost every civilised country of the world except England, exists in the character of a Minister of Public Works. It may be questioned how far any country in which no machinery for the solution of a question of such primary importance has been organised, has any claim to be considered, ad hoc, as entitled to the appellation civilised. It matters little for our present enquiry whether we consider the Minister of Public Works to be a permanent officer, ripe in the experience and apt in the discharge of the functions of a consulting engineer, or whether we regard him under the less favourable, but more usual conditions, of being a man without special education for that or any other administrative function, whom the ebb and flow of party strife has wafted to the arm-chair of the Minister, and whose function consists in acting as detent to a well-organised and efficient staff. Whether of his own knowledge, or as crammed by his secretaries and heads of departments, we will consider the imaginary Minister to be a man who rises to the level of his position.

What, then, he will ask himself, is the question raised by the Royal President of the Society of Arts? It is that of the provision of water for domestic consumption for a rapidly increasing population of twenty-five millions of people. What is the source of that water? The reply is simple. Yet, simple and undeniable as it is, a very large

proportion of educated people will hesitate when they hear it pronounced. The sources are many,' they will say; there are rivers, brooks, lakes, ponds, and wells. Above all, there is the never-failing resource of springs. Yes, no doubt that is the secret. Let us tap the springs; let us utilise the springs. Eureka! How stupid the world has been not to think of it before! Please your Royal Highness, we most respectfully recommend that the attention of surveyors and engineers throughout the country be turned to the utilisation of the springs.'

Let us suppose the Minister, thus advised, to turn to some rugged counsellor of the stamp of the elder Stephenson. You must provide me with a plan,' says the Minister, 'for the proper utilisation of the springs.'First,' replies the sturdy Northumbrian, I must ascertain the facts of the rainfall.' 'What has that to do with it?' is the naturally elicited question. 'Everything.' 'Explain yourself.' 'First, every drop of fresh water that exists through the country has descended on its surface as rain.' 'I can not at all admit that,' the great man will be very likely to rejoin. You find springs, lakes, and rivers to be much the same in wet or dry years. There may, of course, be some addition to their volume in a very rainy season, but that is all. When we have had a very dry summer, and no rain for months, the meadow land may have suffered, but that is only because we have no good system of irrigation. Look at Egypt-look at parts of the Punjanb! It never rains there. And what do you say to the Nile and the Indus?' 'I say, sir,' replies the engineer, 'that the Nile is fed by the great equatorial rainfall of Africa, and that her floods can be traced, almost to an hour, to the solstitial rains of Abyssinia;' whilst the Indus has its springs amid the rains and snows

of the Himalayas. Not only is it certain, as matter of scientific theory, that the internal waters of a country are fed solely by rainfall, but we have instances of serious modifications of climate and diminution of water supply where such barbarous destruction of forests has been carried on as to diminish, or even banish, the rain-clouds. Dr. Hooker wrote to the Earl of Kimberley in 1873: There is good reason to think that in tropical countries the removal of wood operates effectually in reducing the rainfall. . . I have lately received an account of the deterioration of the climate of some of the Leeward Islands, which affords a melancholy confirmation of what I have urged above. The contrast between neighbouring islands is most striking. The sad change which has befallen the smaller ones is, beyond doubt, to be ascribed to human agency alone. It is recorded of them that, in former times, they were clothed with dense forests, and their oldest inhabitants remembered when the rains were abundant, and the hills and all uncultivated places were sheltered by dense groves. The removal of the trees was certainly the cause of the present evil.' 'The island of Curaçoa,' says another writer, 'was, within the memory of living persons, a garden of fertility; but now whole plantations, with their once beautiful villas and terraced gardens, are nothing but an arid waste; and yet, sixty miles away, along the Spanish Main, the rankest vegetation covers the hills, and the burdened clouds shower down abundant blessings.' These facts, with numerous others that are cited in an article on Forest Management in No. 290 of the Edinburgh Review, will suffice to show that the destruction of woods and forests diminishes the rainfall of a country. They are not without appropriate interest in the present enquiry, as showing the question

able wisdom of that modern farming, which fells every tree and replaces shady hedge-rows by wire fences. As rainfall diminishes, springs and rivulets dry up; and how, if rain altogether cease, a country is converted into a perfect desert, from which vegetation is altogether ab

sent.

6

Our supposed Minister, if he be a wise man, will throw up his cards here. You are more at home on the subject than I am,' he may say; tell me at once what you advise?' Coming thus far, let us drop the form of interlocution, and try to take such a grasp of the matter by the small of the back as was the wont of our noble old Northumbrian wrestler.

Every drop of water that is consumed by vegetable or by animal organisms in Great Britain has previously descended on the surface of the island in the form of rain. 'By the heat of the 'sun,' says a contemporary writer, darting directly down upon the tropical seas, there is evaporated from their surface, within the year, a body of water that is estimated at seventeen feet in depth. Ascending imperceptibly, this enormous mass flies on the aerial currents, in visible or invisible vapour, until it is wrung forth, as from a sponge, by the agency of chilling blasts, or by the attraction of mountain summits. Weeping through thirsty moss, collecting in peaty hollows, percolating through gravel and sand, the rain that has fallen follows the slope of the watershed, forms the cradle of infant streams, babbles in rills, brooks, or torrents, and finally rushes in a river to the sea.' Nor is it in sub-aërial rivers alone that this great seaward movement of the rainfall is carried on. In pervious soils, in gravels, sands, and even in chalk, a subterranean current is in constant movement. Thus, to understand what are the sources for the supply of the water which is

demanded for domestic or for any other purposes in our island, the first and indispensable requisite is to acquire a knowledge of the facts of the case. We must ascertain how much rain actually falls on every portion of the surface of England. And we must trace the progress of that rainfall, whether in the shape of evaporated moisture, of rivers and brooks, or of subterranean flow. When we can strike the great hydraulic balance, -can say, on the one hand, what is the volume of water that we annually receive from the sky, and, on the other hand, how that volume is distributed and carried to the ocean-we shall be in a position to reply to any questions with reference to the impounding or the utilising of any portion of that supply. And until this is done, any attempt to deal with the subject must be vague, tentative, and puerile.

With regard to the first point, the amount of the rainfall of England, we are in possession of much

valuable information. This fact is not due to any national movement, to any ministerial intelligence, to any organised action of scientific men or bodies. It is due mainly to one man, and to the sympathy and interest which he has shown how to awaken in a large body of entirely unremunerated assistants. Mr. G. J. Symons's annual publication, entitled British Rainfall, gives the distribution of rain over the British Isles, as observed at nearly 2,000 stations by independent and unpaid observers. No book issues periodically from the press that does so much credit to the English public in the way of proving how large an amount of self-educating energy-directed not to sordid, but to purely scientific, ends-has been called forth by the invitation of one serious student of nature. To Mr. Symons we owe the knowledge of the remarkable fact that certain mountain peaks and passes of our

lake country are bathed with an annual rainfall such as we should not have expected to be able to measure nearer London than the ghauts of Hindostan. At the Styehead Pass, in Cumberland, fell in 1872 the amazing quantity of 244 inches of water. At Taylor's Fell, in the same neighbourhood, a fall of 224 inches was gauged in the same year. The driest part of England in that same year (or at least the place where the lightest rainfall was gauged) was at Silsoe, in Bedfordshire, where Mr. Trethewy measured a fall of 26.18 inches of water. The rain over the different districts of England ranged, in 1872, in amount between these two extremes. To ascertain the total quantity that fell on the whole country, it is necessary to have more exhaustive observations than can be supplied by amateur observers. It is the opinion of Mr. Symons, and there is, therefore, the best reason for concluding it to be the case, that the rainfall of 1872 was 36 per cent. in excess of the average rainfall of the country. The driest year over which the observations extend was 1870. In that year the rainfall was 18 per cent. below the average; or, in round numbers, less by 50 per cent. than in 1872. By taking the pains to abstract the returns for the latter year published by Mr. Symons, to average the rainfall of each of the ten districts into which he has divided England and Wales, and to multiply such average depths by the areas of the several districts, we come to the conclusion that the quantity of water which, taking one year with another, annually falls over the island south of the rivers Tweed and Solway, is one hundred and twenty-seven milliards of tons, or, to put it in figures, 127,500,000,000 metric tons of water. Eighteen per cent. deducted from this quantity still leaves the enormous volume of one

hundred and four milliards of tons of water, which falls on our island, and makes its way to the sea annually. This is rather more than 10 per cent. more than the annual flow of the Nile, according to the careful and accurate measurements of Mr. Fowler, C.E.

of

If we take the population England and Wales at the round figure of 24 millions of souls, we thus find that it takes less than I per cent. of the whole rainfall to supply every want of that population with something like a metric ton of water per week. This is a quantity equal to the utmost demands, not only of social comfort, but of sanitary science. We see

that even the small amount of exact information which has been collected by praiseworthy amateurs, when brought to bear on the vast, vague question of rural and urban water supply, very considerably reduces that aspect of difficulty which has called for a Royal enquiry.

It is, however, obvious that as the rain gauged in the lofty mountain passes of Cumberland is nearly tenfold the quantity, over equal areas, of that which falls on the sandy plains of Bedfordshire, general averages are not enough to guide the engineer. He must be in possession of maximum and of minimum, as well as of mean, rainfall. He must also be acquainted with the maximum and minimum of each independent catch-water basin. We find that this consideration takes us a step farther in the investigation.

For the clear designation of the exact water capacity of each district and sub-district of the country we require the aid of a special branch of the craft or science of the engineer, namely that of the hydrological surveyor. In other words, we require a hydrographical map of England. With full information collected, tabulated, and clearly