train of the weight and character of those which are carried on the elevated roads, with an equal load of passengers, can be moved by electric motors with greater rapidity, with greater safety, and with greater comfort in these tunnels than on the surface or elevated lines. The inhabitants of American cities have been in some sense fortunate that a combination of circumstances—some even arising from pernicious causes-has heretofore prevented the adoption of any intermural rapid-transit systems, which in the past would have been from necessity somewhat analogous to the old London underground railway. It required a combination of the genius of a civil engineer like Greathead with the latest inventions and improvements devised by a succession of electrical engineers, to bring together a method of construction and a system of traction which, for the present at least, and probably for many years to come, will prove to be the adequate and satisfactory system of rapid transit for large cities.

The question of cost, however, is another element to be considered before any system of intermural transit may be regarded as feasible. In this matter the Greathead system, unless compared with one that filches its right of way and then trusts to the chances of litigation to escape from the consequences, offers many advantages over every other. In the first place, it occupies space not hitherto available for any other purpose and therefore of little or no value. Secondly, although the cost of construction is higher than that of an elevated railroad through a street for the occupancy of which little or no payment has been made, its cost of maintenance is so slight as compared with the cost of maintenance of such an elevated structure (which is practically a bridge, and which, to be safe, must be renewed in all its parts in the course of one decade) that the amount available for interest payment and dividends is larger-or, in other words, the net cost of operation is smaller-by the Greathead plan than by any other.

When the project of the Central London Railway, which is constructing and is to be operated on this system, was before the House of Lords for final sanction, at one of its sessions in June, 1891, Mr. Hamilton Smith, managing director of the exploration company, asserted that this railway would carry from 25,000,

000 to 30,000,000 passengers a year; and the "Daily Telegraph," in its issue of June 26, 1891, agrees with him in saying that this and the further estimate that in five or six years this number would, in all probability, be doubled, was not an exaggeration. In speaking of this system in the same editorial, the Telegraph" says that the decision of the Lords' Committee (virtually the sanction of Parliament) in approving the bill marked the commencement of a new era in the history of Metropolitan intermural communication.

"It is the first step toward the establishment of that direct railway system which this City of Magnificent Distances [speaking of London] needs more than any other in the world, but for which it has had to wait for so many years. For the first time in his life the resident will cease to be restricted by means of communication from one Metropolitan point to another which, when direct, was not rapid, and, when rapid, was not direct." The writer goes on to say that he looks forward with confidence to the time when many such lines will be established:

“Trains running noiselessly at many feet below the pavements, with no din to bewilder the passenger and no sulphuretted vapor to suffocate him and to poison the upper air through a 'blow-hole,' will present a far more engaging picture to the imagination, besides appealing far less unpleasantly to the senses, than the existing Metropolitan railway service. It will go some way to realize the ideal which the world's capital ought to set before itself in this matter."

This editorial expression applies with great force to New York. The existing means of transit are inadequate to move even the present population; therefore some new road must be constructed, and that at once. Present methods, for reasons too obvious to mention, will not be chosen to supply this public need. The soil of the city of New York, and the great value of real estate therein, the multitudinous service pipes which underlie our streets without system or regularity, the enormous traffic which is done upon them, are all causes combining to make the Greathead system the best adapted for purposes of rapid transit on Manhattan Island. It can go under the most important avenues and the most valuable houses without opening a single highway during construction, and without disturbance of foundations, occupying space of little or no value below the surface, notwithstandingthe great value of the land but a few feet above the tunnels.

It is suggested that the Greathead system, while admirably adapted to clay, silt, sand, or other soft material, is ill adapted to the rock that underlies our island from Fourteenth street northward to above the Central Park, and that in such rock the old system of tunnelling, without lining or with brick arches, must be resorted to. This is a misconception. There is scarcely a continuous hundred feet of the rock underlying the city of New York free from natural fissures. It has also been so blasted, excavated, and disturbed at every point, that, independently of natural fissures, any number of clefts have been created by blastings, to establish streets, to build foundations of houses, and to lay sewers and gas and water mains. The consequence, were the rock excavation under the sewers, steam, gas, and water pipes to be without a gas-proof and water-proof lining, would be that the tunnel would become filled with moisture precisely as though it were in soft material, with the difference that the water and moisture lying in fissures would be under pressure and therefore more dangerous to a brick or rock-lined tunnel than if in clay, silt, sand, or gravel; and the pump would have to be kept at work constantly to eject exudations of the watery filth of a great city, unless the tunnel were constructed through the New York rock by the Greathead system.

There is, therefore, nothing in the nature of the material on which New York City stands which in the slightest degree interferes with the adoption of the Greathead system of tunnelling, if its citizens wish to secure the most perfect system of rapid transit now known.

SIMON STERNE.

A NEW ROUTE TO THE NORTH POLE.

SINCE interest in the polar regions was first aroused by the search for the northwest and the northeast passages, there has been no lack of explorers ready to venture their lives to reach the North Pole itself. Attempt after attempt has been made, but all have failed, though our knowledge of the Arctic regions has slowly but surely advanced until it now has reached latitude 83° 24′ north-the point gained by Lockwood in May, 1882.

But why did all previous attempts fail? The reason is simple enough. The expeditions were everywhere, at a greater or less distance from the Pole, stopped by the drifting floe-ice which formed immense impenetrable masses and in most cases was carried down against the ships by currents from the north. Many bold sailors dreamt fantastic dreams about an open polar sea behind this ice barrier, but such speculations were of no use. It was impossible to penetrate the ice, and to walk over it was not much easier, since it is moved by constant currents from the north; there was no choice left but to return. No land has yet been found on which an advance toward the Pole would be likely to succeed; none of the lands we know seem to extend very far north of the latitude already reached.

Many people think that the North Pole can be reached through the air by a balloon or by balloon-ships, and that it will be so reached one day. I do not deny the possibility of this; on the contrary I regard it as very probable. But the only way at present would be to intrust one's self wholly to the wind, and this is no certain way so long as we have no knowledge of the windcurrents of these regions. A good result must in that case necessarily depend upon a combination of happy circumstances which are not common in the course of an ordinary human life. To go in a submarine boat under the ice would be rather risky, so long as submarine navigation is as little developed as it is at present. But is there no other way to reach the North Pole? It has already been mentioned that most polar expeditions have

been stopped by irresistible currents from the unknown north, carrying immense masses of thick floe-ice. From this fact we seem entitled to draw a very simple conclusion, namely, that if there are opposing polar currents there must somewhere exist one or several favorable currents; for the water carried southward by the polar currents from the unknown regions must somewhere return to these regions. As expeditions have been carried by the ice southward from the very threshold of the unknown region, others may be floated into that region if they can only strike the current on the right side. There we have the way already pointed out; the problem is to find the right place.

If we consider the experience of whalers and sealers who have sailed for a long series of years in the Arctic seas on both sides of the Pole, one singular circumstance must strike us at once, namely, that ships caught in the ice on the side of the Pole near the Greenland Sea are carried southward, and that their crews run, as a rule, no great risk. Not so on the other side of the Pole, north of Bering Strait; ships caught in the ice there drift northward and often disappear, some with few and others with many men on board; most of them probably are destroyed in high unknown latitudes. This fact must lead the thoughtful observer to the conclusion that there are differences in the sea currents which may be used in favor of a polar expedition. Let us, therefore, examine the question more closely.

The most important polar current is beyond comparison that which runs southward along the east coast of Greenland. This has a considerable speed and carries an immense quantity of water out from the polar basin. It fills the whole opening between Greenland and Spitzbergen, with the exception of a narrow belt along the coast of the latter. The breadth of the current must be at least 250 nautical miles. Its depth is difficult to determine, but it runs over the deepest known bottom in the Arctic regions; there are measured depths of 2,600 fathoms. I do not think, however, that we are entitled to assume that the polar currents are usually deeper than 300 fathoms; perhaps not deeper than 200 fathoms. At the depth mentioned the current has a breadth of about 170 nautical miles. It runs, of course, much quicker at the surface than in its deeper parts, and it is