yond this they run parallel to the coast as far as the mouth of the Scheldt, and their direction generally shows the course of the currents.

The rivers falling into the sea on this coast, are the Scheldt, the Zwin, the creeks and canals forming the ports of Ostend and Nieuport, Dunkirk and Calais, the Aa, flowing from Gravelines, the Wimereux and the Liane.

The Scheldt at Antwerp is 1,300 feet wide and its depth 52 feet. It continues its course seaward, mingling its waters with those of the sea, and soon after divides into two branches, the most easterly of which, named the Hout or Eastern Scheldt, flows along the shore of Zuid-Beveland, and falls into the sea between the islands of Walcheren and Cadzand. The other branch passes Bergen-op-Zoom, forming the West Scheldt, which flows along the other coast of Zuid-Beveland, and the islands of Wolfersdyk and Noord-Beveland, and falls into the sea between the islands of Walcheren and Schonwen. A little beyond Bergen-op-Zoom is another branch of the Scheldt, which passes Tolen and joins the Kecten. Here it is said that the Scheldt flowed into the Meuse in the time of Cæsar.

Properly speaking the Scheldt terminates some leagues below Antwerp, for the rest of it may be regarded as arms of the sea, as there is no resemblance between the river and the mass of waters which inundate the islands of Zeeland. Here again, like the arms of the Meuse, are enormous creeks which the sea enters at each tide, flowing to the interior of the country, and which form outlets for the Scheldt and Meuse, presenting traces of those daily inundations which have hitherto been so frequent on the coast of the North Sea. A short distance from the eastern mouth of the Scheldt is that of the Zwin, another creek communicating by several branches with the Scheldt, and which formerly extended as far as Damme, where it formed a considerable port.

The ports of Ostend, Nieuport, Dunkirk, and Calais, are still the remains of former creeks. That of Nienport contains a branch of the Yperlée, which rises a little above Yprès. This little river, which has been cut into a canal, is nearly dry in summer, but during the rainy weather forms a rapid torrent, which inundates the neighbouring country. At three leagues from Yprès flows the Iser, taking its rise at Mount Cassel. Near Dixmude the Yperlée divides into two branches, one flowing to Nieuport and the other towards Oudenbourg and Bruges. This last has several branches, one of which terminates at Middelkerke in the downs.

The Aa rises on the confines of Boulonnais and Artois, and after reaching the foot of the hills forming the boundary of Artois, it flows to St. Omer, thence to the flat country, where it divides into two branches. The smallest is called Colme, and flows to Bergues; that flowing to the left retains the name of Aa, and ends at Gravelines, in the sands, where it forms a small port, communicating with some creeks of moderate size, which serve to irrigate the country.

REPORT OF THE COMMITTEE APPOINTED TO EXAMINE THE FOG SIGNAL, PROPOSED BY MR. DABOLL.

[Those of our readers who are acquainted with the Bay of Fundy are also familiar with the fog signal on Partridge Island. The extraordinary distance at which this is heard, even in vessels in the wind's eye of it, renders it at once the most efficient and desirable that can be produced. Indeed, our own slow methods of bells and gongs are left by it in point of effect in the fog of the dark ages. We have received the following report of a similar apparatus, which we insert for the benefit of those who will take it up, being desirous of seeing those improvements in the aids to navigation on our own coasts that are found on those of our active-minded friends of the United States.-ED.]

The Committee of the Light House Board appointed to inspect the apparatus proposed by Mr. Daboll, for giving signals during fogs, met at New London on the 28th of October, 1859. The members of the Committee present were Captain Tilton and Professor Henry of the Lighthouse Board, and Commander Pennock, Inspector of Lighthouses of the third district.

The Committee proceeded to the lighthouse, (situated about three miles from the city,) where the apparrtus was placed for their examination. They found it in operation, giving signals at regular intervals. The sounding or signalizing instrument consists of a trumpet about four feet and a half long, of a conical form, with a flaring orifice, the exterior diameter of which is eighteen inches. The larger or open end of this trumpet projects through the stone wall of an old house facing the water, while the small end and the working part of the apparatus, are within the building.

The trumpet is furnished at the small end with an ordinary reed arrangement, with a very stiff tongue, and is sounded by a blast from a reservoir or receiver of condensed air. The air is condensed in the receiver by means of a small Ericsson caloric engine, the piston rod of which gives motion to the air pump, by which the condensation in the receiver is effected. The receiver in which the air is condensed is about three and a half feet long, and two and a half in diameter. It is furnished with a safety valve, loaded with about ten pounds to the square inch, but is capable of withstanding a pressure of several hundred pounds. It has also a discharging valve through which the blast of air to sound the trumpet passes. This valve is opened at regular intervals of about ten seconds, and produces a sound in the trumpet which lasts about five seconds. This automatic effect is produced by four cams on the surface of a wheel attached to the shaft of the engine. The valve is opened by means of these cams four times during each revolution of the wheel, and the ratio of the interval of sound to silence can be regulated, by increasing or diminishing the portion of the circumference of the wheel occupied by these cams.

The intervals, as said before, are about ten seconds of silence to five of sound.

The caloric engine, whatever may be its comparative merits for other work, appears to be well adapted to the purpose to which in this case it is applied. It is very simple in construction, easily put in operation, and not, apparently, liable to get out of order. The whole horizontal space occupied by the engine and condenser is ten feet long by two and a half wide. The quantity of fuel required to supply the necessary amount of motive power, is too small to be considered an item of importance. The furnace holds about a peck of coal, and no addition was made to the fire during the time the Committee was making the examination, though the engine was constantly in motion for several hours.

But the properties which more particularly recommend it for the purpose of signals are, that it offers not the least danger of explosion, and no water is required for its operation. Any person possessed of ordinary intelligence and sufficient handicraft skill to attend a Fresnel light, can readily manage this engine, and any one who has not this small amount of practical talent, ought not to be retained in the office of a light keeper of a lens of the first or second order.

The apparatus while the Committee were present, continued in operation for several hours with perfect regularity, and without any diminution in the quantity or intensity of the sound. The Committee had no opportunity of ascertaining the maximum distance at which the trumpet could be heard under favourable circumstances, but the captain of the steamer Commonwealth assured them that he had heard it five miles. In order to ascertain the distance at which the sound could be heard under ordinary conditions, the light keeper was directed to put the apparatus in operation at the time when the steamer in which the Committee were to embark, left the wharf at New Lon don, and to continue the sounding until the vessel was at the distance of several miles. This was done, but the conditions were unfavour able to hearing, and the result could not be considered a proper test of the power of the trumpet. A strong wind was blowing nearly in an opposite direction to the sound, and the motion of the wheels of the steamer and of the vessel through the water produced so much noise in the immediate vicinity of the hearers, that the distant sound was neutralized at a comparatively short distance. It was not thought advisable at a late hour of the night to request the captain to stop the engine of the boat. The distance at which the trumpet was heard under these conditions, was about two or two and a half miles.

Various attempts have been made under the direction and at the expense of the Light House Board, to introduce means for giving reliable signals during foggy weather, but none of these have proved satisfactory. Bells sounded at intervals by clockwork, and whistles blown by high pressure steam have been employed. The sound of the bell cannot be heard amidst the noise of the breakers at a sufficient distance, and if heard it is extremely difficult to locate the

sound. In addition to these the automatic arrangement which has been adopted to give the bell motion, is liable to get out of order, and requires the aid of an additional keeper to be in readiness to assist in winding it up on the occurrence of a fog.

From the testimony collected by the Committee, it appears that the steam whistle can be heard farther and be more readily recognized than the bell; but to furnish the steam by which it is blown a constant supply of fresh water is required, which in some localities cannot be obtained. Besides this a small engine is necessary to pump the water into the boiler, and to open the valve at the proper intervals. The Committee also think it probable that a greater amount of motive power is required to produce a given amount of sound from a whistle blown by steam, than by a reed trumpet sounded by a blast of condensed air, but on this point they have no positive information. From all the facts which the Committee have been able to gather, they are of opinion that the apparatus exhibited to them by Mr. Daboll, at New London, offers the most promising means of producing sounds for signals with which they are acquainted.

1.-The trumpet of this apparatus gives a peculiar sound, which cannot be mistaken for any other.

2. It directs the whole force of the agitation of the air to that part of the horizon in which the sound is to be heard.

3. The engine is easily worked and not liable to get out of order, or subject to explosions.

4.-The intensity of the sound may be indefinitely increased.

But in a matter of so much importance as the means of giving signals during fogs, and which has occupied so much attention in this country and in Europe, the Committee would advise that previous to the adoption of this apparatus, or to giving it the sanction of the Board, a series of experiments and observations be made in regard to it, under different conditions, and in comparison with the steam whistle and the ordinary fog bell; and for this purpose they would recommend that the apparatus now at New London, be purchased, provided it can be obtained at a reasonable price, and the Board have the means and the power.

JOSEPH HENRY,

Chairman of Committee on Experiments.
A. M. PENNOCK,

Commander U.S. Navy.

THE WESTERN DIVISION OF THE MEDITERRANEAN.-Winds and Weather.

If we consider the contour of the western basin of the Mediterranean, or rather of the space comprised between the islands of Sardinia and Corsica and the Strait of Gibraltar, we shall at once perceive the tendency of the coasts of Africa and Europe to converge NO. 5.-VOL. XXXII.

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towards each other; so much so, that between Cape de Gata and Cape Fegalo they are not more than eighty miles asunder. From thence to the westward this tendency continues in the parallel of 36°, as far as the mouth of the Strait. Here the two continents approach so closely, that in the vicinity of Tarifa the channel between them is less than eight miles across. This arrangement of the continental shores, along with the high ground of which they are formed, produces distinct alterations in the direction of the wind, alterations which become the more perceptible the nearer the observer is to the mouth of the Strait.

These currents of the atmosphere being promoted by diversities of temperature in the two shores, there is perhaps no place where greater modifications of this nature take place, than in the space of sea separating Europe and Africa, and limited to the eastward by the high lands of Corsica and Sardinia. Besides, the coasts of Spain and with its Gulfs of Lyons and Valencia to the East, and the Strait of Gibraltar to the West, is sufficient with these features to produce changes in the direction of the wind.

For instance, when a strong N.W. wind is blowing in the Gulf of Leon, it becomes North, more or less strong, when it has reached the Balearic Islands, and even N.N.E. at Algiers, and N.E. in the Gulf of Valencia, is changing to E.N.E. as it reaches Cape Palos on the coast of Mureia, is due East when it passes Cape de Gat, follows the narrowing of the Mediterranean in the direction of the Strait, where it is as strong as in the Gulf of Leon, having regained its strength in its course throughout this great distance.

In summer time it is also common for a N.E. wind to be blowing in the channel between the coast of Spain and the Balearic Islands while it is S.E. between these islands and the African coast, and West or S.W. between the Strait and the meridian of Cape San Antonio.

The N.E. wind which blows along the western coast of Algiers becomes due East when it enters the Strait following its shores; and if beyond Sardinia the S.E. wind is blowing, it falls in the Strait, changed to East, the direction given to it by the African coast.

A similar case occurs with westerly winds. If they are from the S.W. or N. W., then they pass through the Strait as if they were due West, and continue thus through the Mediterranean as far as the meridian of Cape de Gat, while on the coasts of Spain and Africa they are S.W. or N.W., and in the middle of the Mediterranean are following their course due East.

The winds of the Strait, however, do not always undergo such changes, whether from East or West; although the effect produced by the configuration of the coasts of those continents holds good ordinarily and when the atmosphere may be considered in a state of quietness: in such cases the easterly or westerly wind is blowing moderately at either end of the Strait. When a S.W. gale is blowing which penetrates into the Mediterranean, it preserves its direction and even strength and sky, without the trend of the shore in the Strait altering its course, as far as and beyond Corsica and Sardinia, hauling