The mean place of the water is next treated of, and Captain Beechey recommends this method of obtaining a standard for the reduction of the soundings in all nautical surveys. The operations in Ireland abovementioned had shewn with what accuracy a permanent point of reference might, by this means be obtained: and we find in Captain Beechey's observations that in four consecutive years the extreme difference of the means amounted to only two inches. Such small differences can, however, only be obtained by a series of observations of both day and night tides, and it is remarked that the mean level of spring tides is higher than the mean level of the neaps.

Sections of the tide-wave throughout the Channel are given and referred to, in order to shew that the water having acquired an impetus will maintain its course for a considerable time, and overrun an ad· vancing tide-wave, although ascending a considerably inclined plane; and to exemplify that there is no necessary connexion between the direction of the stream and the rising or falling of the water, for in these instances it is seen that the tide-wave is rolling in, making high-water in its progress along the Channel, whilst the stream is passing out in spite of the undulation.

We now come to the most interesting part of this paper:-Captain Beechey having reported upon the phenomenon of the Irish Sea as determined by his own observations, takes up the subject of the tides generally, as they affect the navigation of both the English and Irish Channels. Availing himself of the observations which had been already made, especially those of Captain Martin White, he endeavours to reconcile and account for the apparently contradictory observations on the courses of the stream throughout the Channel.

The remarkable similarity of the geographical feature of the English and Irish Channels rendered it probable that a similarity of tidal phenomena would also appear, upon investigation, and combining the information which had been procured in the Irish Sea, with the observations which had been made in the English Channel, it was evident to the author that the water in all the outer part of both Channels was influenced by forces acting in opposition to each other, or in other words that there was a tide in the offing, whose streams of ebb and flood did not correspond with those of the inner waters; but we shall let Captain Beechey speak for himself. He gives it as his opinion that "The great offing stream at the entrance of the English Channel extends its influence as far up as Cape La Hague, beyond which, owing perhaps to the sudden contraction which there occurs in the Channel, the stream suffers no interruption, but, as in the Irish Sea, passes up and down the Channel six hours nearly each way as far as a line joining Dungeness and Cape Grisnez, the apparent virtual head of the tidal channel. Here the influence of the North Sea stream begins to be felt, and here, as in the Irish Channel, again the time of high and low water at the virtual head of the tide regulates the turn of the up and down stream along the whole channel as far as the contraction. Beyond this the offing stream being governed by its own high water, and that occurring at

about six hours earlier than that of the head of the channel, the offing stream either encounters the returning streams from the Channels, or withdrawing its water, solicits their streams and thus alters their course, making them for the most part set across the Channel in curves more or less bent, as the spot is more or less removed from the offing; so that there seems to be but one hour's tide each way that passes clean down the Channel from Beachy Head to Scilly, and round the Land's End to Bristol. The outgoing stream from Beachy Head encounters the ingoing stream of the offing tide somewhere about the Start Point, and both are turned down into the great Gulf of St. Malo, which seems to receive the accumulated waters of these opposite tides.

"Whether or not this influx is instrumental in raising the water here to the extraordinary height of 47 feet perpendicular range at springs, or whether it be owing to its form and position as regards the advancing tide-wave, I leave to those who are competent to decide; but it is a coincidence that cannot escape observation, that this spot, like the Bristol Channel, is the concentration of streams from opposite directions; that it has its waters raised to the same extraordinary elevation nearly to a foot, and that its time of high water is nearly the same.

"On the change of tide, this great bay, like the Bristol Channel, as it received so it returns its waters in opposite directions; the tide splitting somewhere between Alderney and the Start."

In the course of this investigation many coincidences seemed to assimilate both the geographical feature, and the tidal phenomena of the two Channels. "If," observes Captain Beechey, (6 we compare their extent and configuration, we shall find that the English Channel, reckoned from a line joining Ushant and the Land's End to the extent of its tidal stream, is 262 geographic miles, and that the Irish Sea, taken from a line joining Cape Clear and Scilly to the end of its tidal stream, is about 265 geographic miles. In both Channels there is a contraction about midway by the promontories of Cape La Hague, and by St. David's Head, and at very nearly the same distances from the entrance. These contractions are in both cases the commencement of a regular stream flowing six hours each way, and the turn of the stream throughout coinciding with the times of high and low water at the vertical head of the Channel, situated in both instances about 145 miles above the contraction. Below this contraction the stream in both cases varies its direction nearly every hour according to the force exercised over it by the stream in the offing. In both cases again between the contraction and the southern horn of the Channel there is situated a deep estuary: the Bristol Channel and the Bay of St. Malo, in which the times of high water coincide, and where, in both cases, the opposing streams meeting off the mouths, pour their waters into these gulfs; and where the tides in both cases rise to the extraordinary height of 47 feet at the springs.

From the Land's End to the meeting of these streams in the Bristol Channel is seventy-five miles, and from Brest to the meeting of the streams off Guernsey the same. A still further coincidence is pointed

NO. 2.-VOL. XVIII.

L

out in the phenomena of these Channels. In one at a place called Courtown, a little above the contraction of the Strait, and at 150 miles from Cape Clear, (its entrance,) there is scarcely any rise or fall of the tide, and in the other channel (about Swanage) similarly situated above the contraction, and just 150 miles from the Land's End (the entrance of the Channel) there is only 5 feet rise of the water at the springs. In both cases these points of small range of tide are situated on the opposite side of the Channel to that of the great range abovementioned; and in both cases these spots are the nodes of the tide-wave, on either side of which the times of high water are reversed. Again, there is traced a similarity in an increased rise of the tide on the south-east sides of both Channels abreast of the virtual head of the tide; viz. at Liverpool and at Cayeaux, when the spring ranges are respectively 32 and 34 feet."

Captain Beechey pursues the comparison still further in the progress of the tide-wave along both shores, and between the situation of the node placed by Professor Whewell in the North Sea, and a corresponding point of small range and immersion of phase at the back of Kintyre: the node in the northern being, curiously enough, situated as nearly as possible at the same distance off the head of the tide at Dungeness as the node at Swanage is on the opposite side of it; and the node at Kintyre is about the same distance from the meeting of the tides off the

Isle of Man, as the North Sea node is from the meeting of the waters off Dungeness; and is similarly situated with regard to the node at Courtown as the North Sea node is with regard to Swanage.

We regret the inability to do more than give a diminutive sketch of one of the many interesting plates which illustrate Captain Beechey's paper.

Much of the reasoning from which the foregoing conclusions as to the motion of the streams in the two Channels was derived, was based upon data collected from various sources, and Captain Beechey being desirous of testing his views by a full investigation of the whole of the tidal phenomena of the Channel, the Admiralty, at the request of the President and Council of the Royal Society placed a cutter at his disposal, and we have just learnt that the observations have confirmed in a most satisfactory manner the comprehensive view he had taken of the subject. The investigation it is understood will be continued in the ensuing summer, and when completed will no doubt be published for the benefit of navigation.

The paper is illustrated by various diagrams shewing the form of the tide-wave of ranges varying from 8 feet to 44 feet, and for the reduction of soundings taken at any hour to low water, &c.

We cannot conclude without congratulating the seaman on the introduction of this simple and reasonable plan of referring the times of the turn of the stream to the phase of the tide at the head of the estuary or channel, and which in a channel accessible to a tide-wave at both extremities, Captain Beechey thinks will be situated somewhere near where the meeting of the tides occurs.

ASCENT OF THE SPITS KOP MOUNTAIN.-Cape of Good Hope. (Concluded from page 22.)

BEING at Graaff Reinet, I embraced a good opportunity which presented itself of making the tour of the Sneuwbergen, or Snowy Mountains, and ascending the Spits Kop or Compass-Berg, the highest peak in South Africa; and if beautiful scenery, a heavenly climate, and the hospitality which is to be met with on the road, have any charms for any of your numerous readers, I would say make this trip by all means. Having procured horses, the earliest dawn of the 2nd of September, saw myself and an old friend and fellow-traveller, Mr. Eden Baker, on the road, accompanied by Mr. R. Southey of this place, who intended riding part of the with us. way We proceeded, not by the direct road to the mountains, but took the longer road through Pretorius Kloof. This romantic ravine, in length upwards of thirty miles, contains in its bosom many fine farms, and the Sunday River, the banks of which are luxuri

* In page 71 "Courtown" has been inadvertently printed "Camtown."

antly clothed with mimosas and willow trees of an enormous growth. The latter droop their elegant branches quite down to the surface of the waters, whilst the mountains which tower above you on all sides render the valley a complete picture. A curious circumstance is worthy of remark in this river. The stream in many places disappears suddenly in the sand, and rises again after a subterraneous passage of a mile or less; this occurs frequently both above and below the Kloof.

After crossing the river twelve times in as many miles, at some places a flowing stream, at others a dry water course from the above-mentioned circumstance, we arrived at the farm of Lieut. Bingham. In the afternoon we intruded on the kindness of another family, Mr. Siesching for a dinner, to which, with the usual frank hospitality of Africa, we were made most welcome. Towards sun-set we emerged from the Kloof after having crossed the Sunday River twenty-five times. At this spot we remarked the curious appearance of the rocks and stones which have, apparently, been piled and heaped together with the utmost regularity, resembling ruined towers and fortifications, by a hand more powerful than that of puny man. These rocks abound with the rock rabbit or hyrax. At the close of the day, we reached the farm of Mr. Southey, where we slept. Over the hills which surround this place, the sharp conical peak of the Spits Kop appeared floating in mid air, having its shoulders enveloped in fleecy clouds. Daylight saw us in our saddles, cantering briskly over a delightful valley thickly strewed with spring boks.

Our party being encreased to five, and a hard frost having covered the country, we did not draw bridle for nine or ten miles, when we ascended a lofty ridge of the Sneuwberg; on the other side of which we perceived another extensive grass plain of many miles extent: the Spits Kop and neighbouring mountains bounding the view. From this eleva ted spot the eye wanders over a great part of these fine mountains, whilst numerous farm-houses enliven the plain below. At Quagga's Viey our companions parted from us, and we struck off in a southerly direction, having already passed to the northward of our destination-the Spits Кор.

After a ride of a few hours through the most delightful scenery, we again came in sight of the Spits Kop, whose gigantic form was seated on a high range of mountains, having a grassy plain at its own immediate base. This range was similarly situated, being on the summit of another range, thus forming three prodigious steps from the plain to the summit of the peak.

rais.

At mid-day we descended a ravine, whence the Sunday River takes its course, and partook of a Dutch boer's dinner at the house of C. MoAt this place a high ridge of mountains runs east and west, dividing the rivers flowing north and south; those on the south side flowing into the sea, and those on the north into the Orange River, with the exception of the Little Braake River, which, rising on the north side of the range, flows along the side of the Roode or Rhinorter Berg, and suddenly turning to the south, passes the eastern spur of the Scherding Berg, and falls into the Great Fish River at Salt Pan Drift. After pur