"From the sketch it will be seen that this is a series of dark cumulous-looking clouds, like festoons of dark drapery, over a considerable portion of the sky, with the lower edge well defined, as if each festoon or 'pock' was filled with something heavy; and generally one series of festoons lies over another, so that the light spaces between resemble an alpine chain of white-peaked mountains. It is essential that the lower edge be well defined; for a somewhat similar cloud, with the lower edge of the festoons fringed or shaded away, is sometimes seen, and followed by rain only."

He then describes three other observations of the cloud, and concludes as follows:

"It is remarkable that on these three last occasions (which he cites) the storm burst out in, or veered to, a direction almost exactly opposite to that in which the festooned clouds had travelled. It is difficult, in other cases, to explain why a particular kind of weather follows a particular form of cloud; and it would be premature to attempt to do so in this case, till observations are made with this view; so at present I rather invite than offer explanation; but I may say that as the cumulous cloud is the precursor of coarse weather, so this particular form of it is always the precursor of a gale, and that I cannot look at it without being reminded of Sir J. Herschel's experiment of pouring into a large glass vessel fluids of different densities, which do not mix, and which have different colours. An undulatory movement impressed on such a system disappears very speedily from the surface of the uppermost fluid, but continues long after to agitate the lower strata. This cloud, then, may be caused by masses of moist air descending, and forcing their way through drier and colder air; for its form suggests air diffusing itself downwards, just as the form of the cumulus, or the steam from the steam engine, suggests diffusion upwards. If this be so, it shows the moist equatorial current in greater strength than usual, and an uncom monly quick mingling of air currents, differing in temperature and moisture-the very conditions of a storm. This cloud is well known, and much dreaded by Orkney sailors."

Mr. Jevons's illustration is on a very small scale; he gives an imagi nary section of a thunder-cloud near Sydney, in which the form of cloud in question is described as "the appearance of dropping portions of cloud at foot or back of storm."

In the paper he gives two experiments to show how the development of the cirrous may be imitated. In Experiment I. he takes a weak solu tion of sugar, acidified with muriatic acid, and warms it till its specifie gravity is 995. Placing this in a beaker glass, he introduces beneath it; by the use of a long-necked funnel, a very dilute solution of nitrate of silver in pure water.

The curdy precipitate of chloride of silver is at once formed in filaments like those of the cirrous, which sinks to the bottom gradually, according as the supernatant syrup becomes cooler and heavier.

In Experiment II. the silver solution is poured in gently above the syrup, when "but little cloud at all will be seen to form, even after a considerable length of time; and whatever may happen to be caused by accidental disturbance, will lie in a uniform or streaked flat sheet at the surface, where it is produced, until it finally subsides to the bottom by its own density."

He then remarks:-"It will, perhaps, have been observed, in our experiment No. 1, that the streams descending from the upper stratum into the lower, often end in little knobs, or drops, or scrolls, of a peculiar and interesting shape. I do not understand why the descending streams should differ in shape from the ascending ones, which, generally, but not always, end in evanescing points, though it might arise from the tendency of chloride of silver to subside, as mentioned before; but it is remarkable that similar appearances are often to be seen on the under surface of dense cirrostratous clouds, especially at the front or tail of a thundercloud (as shown in the figure). Sometimes these drooping portions of cloud, or droplets, seem to come in contact with dry air, when their well-defined form is destroyed, and a fibrous or fur-like appearance only remains. They appear to be truly portions of subsiding cloud.”

It will be seen, therefore, that Dr. Clouston and Mr. Jevons agree as to their idea of the formation of the pocky cloud, from the contact of two strata of air in very different hygrometrical conditions; but there is nothing in Dr. Cloustons account to support the view propounded by "J." in Nature, that the phenomenon occurs when the cloud is about to break up. In fact, he expressly points out the modification in its form which indicate this.

M. Poey is disposed to attribute the formation of the cloud to electricity; at least, I cannot gather any other conclusion from his letter, although he does not expressly state how the electricity acts.

A similar view is entertained by Dr. John W. Moore, of Dublin, a most careful and accurate observer of meteorological phenomena, and especially of clouds. I subjoin a letter which I have recently received from him on the subject:

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40, Fitzwilliam Square West, Dublin, November 15th, 1871.

"My dear Mr. Scott, The letters in Nature on a new (?) cloud were interesting; but the discoverer need not have described it as being very rare. So far as I could gather from his description, it is the form of cloud which I have long noticed under the following conditions:"1. In some thunder-storms portions of the lofty cirrus and nimbus

exhibit the appearance in question, the under aspect of the cloud being gathered up in round folds.

"2. Often in cyclonic systems, at the moment when the wind is changing, the cirro-stratus layer of the clouds presents a similar form. And, lastly, frequently,

"3. In showers of hail the high cumulo-stratus becomes puckered, as in the new cloud.'

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Considering the above conditions, it appears to me that two elements are required for the production of these phenomena.

"1st. A rapid condensation of vapour, and

"2nd. High electrical tension.

"From the above consideration I think it would be better to regard the appearance, not as a new form of cloud, but as belonging to clouds of various kinds, under certain conditions.-Yours very truly,

We may, I think, reconcile these two views by the consideration that the contact of two masses of air, at very different temperatures, and in very different hygrometrical states, are precisely the conditions which give rise to the development of electrical action in the atmosphere, and to thunder-storms, so that a high state of electrical tension would accompany the forcible intermixture of a damp with a dry stratum of air.

I profess myself unable to see how electricity could produce any such modification of the form of a cloud, while we know, by experiment, that the appearance may be reproduced by gradually mixing two fluids of slightly different specific gravities.

It may be interesting to give, in conclusion, one of Dr. Clouston's notices, showing the value of the cloud as a premonitory symptom of a

storm :

"Another observation of this cloud was on 10th March, 1864, when I noted, in the morning, light fleecy clouds, in rapid motion, below compact dark ones. At 3.30 in the afternoon, the pocky, or festooned clouds, were seen for ten minutes to the westward, moving before the south wind, probably not more than 300 or 400 yards up; and when they blew past, a more bright and quiet sky appeared in the west, and about 7 p.m. red-coloured aurora.

"Nothing remarkable occurred that night, and next forenoon was so fine and bright, that I was induced to go to Stromness, about six miles off, to bring home a member of my family, though still under some dread of the festoons.

"We started for home in an open gig, nearly twenty-six hours after their appearance, during a flat calm, and I began to doubt if there would be any storm at this time; but I soon paid for my incredulity, for at 5.30, or just about twenty-six hours after the festoons, such a sudden

storm of N.N.W. wind burst in our faces, accompanied with quantities of wet snow, that though we persevered for the remainder of the six miles we had to drive, it was decidedly the worst weather I have travelled in for more than half a century; and it was only after the breaking of an umbrella, and losing of a shawl, that we reached home in a wrecked condition. I found by the registering anemometer that the wind suddenly commenced thus, with a velocity of nearly sixty miles an hour, and continued so till after midnight. This obliges me slightly to modify my former opinion, that it was always followed by a storm or gale within twenty-four hours;' for on this occasion it was twenty-six hours afterwards. On 10th the barometer stood at 29.236 in the morning, and 28.978 in the evening, and on 11th at 28.938 in the morning, and 29.108 in the evening. On 10th the wind was S.W., force, 1 in the morning; and S., 2 in the evening; and on 11th, W.S.W., 1 in the morning; and N.W., 4 in the evening.

MARINE PAINTINGS IN THE ROYAL ACADEMY.

COMMUNICATED BY AN OLD SAILOR.

WHETHER the Nautical Magazine finds its way into the studios of our painters we cannot say, nor can we say whether our strictures of last year have been pointed out to the "Hanging Committee," who have in consequence retained a sailor with a view to exclude from exhibition, marine paintings in which the water would never float any ships nor the ships float on any water; but we learn that the seaman's eye is less offended by incongruities in shipbuilding, proportions of spars and sails, and position, than it has been for some years. Certainly the number of marine paintings is fewer than usual, but of the few there is little to offend the eye of a sailor in matters of detail. We still maintain our opinion that it is as necessary to the artist, who adopts marine painting as his special line, to study the proportion of ships, spars, sails, and all pertaining to the subject, as it is for the sculptor to study anatomy. The following are the observations of our critic:

The first picture that struck me is not strictly speaking a marine painting, although its subject may be considered marine. At all events, I feel assured I shall be pardoned for drawing attention to Mr. Graham's beautiful picture, "The cradle of the sea-birds." It has not fallen to the lot of the many to have had a boat cruize on a fine day under such cliffs as are here depicted, but to the memory of those to whom it has, this picture will bring back vividly all the beauty, and I

may add, awe and delight, experienced then. The rich green, where a ledge has afforded a rest for vegetable growth, the peculiar haze almost invariably seen at the base of sea-washed cliffs, the busy multitude of sea-fowl, the darkly stained rocks, all are there, and represented with such force and reality that it was difficult to withdraw my attention from it. I was particularly charmed with Cooke's "Hastings luggers coming on shore in a breeze" (No. 246). The sea is refreshing, and the life and action of the boat, the truth of the sails and colouring, struck me as rendering it one of the best pictures. Out of the four paintings by Hook, there cannot be a doubt that one at least, "As jolly as a sand boy," will rank among his best efforts. It is a pleasing picture and captivates at sight. I cannot quite say that of his "Between the tides" where the rocks are stiff, but in all the four we cannot but congratulate Mr. Hook in departing from his almost stereotyped green. The nearest approach to this objectionable colour is in No. 265, "Gold of the sea," where the sea and land are of too crude a green. They are redeemed somewhat by the figures and fish in the foreground. "The South Stack Lighthouse, Holyhead: gale moderating," by R. B. Beechey, a masterpiece of water painting, and most certainly the correct drawing of the disabled ship, adds greatly to the value of the picture. There is, however, a want of that misty haze that is always seen on the shore after a heavy gale. In "Sailing free," C. Hunter, the water strikes a sailor as being frittered and woolly appearances which are not warranted by the time of day, or state of weather. The wave thrown off from the boat's bow is not correct; the glimpse of sunlight through the clouds on the water is natural and is the best part of it. Near it is a much more pleasing picture, by a Dutch painter, H. W. Mesdag, and although the water in his "Fishing smack coming into Scheveningen" is more like that of a sea breaking over a bar, it is generally good in colour. I was also greatly pleased with Mr. Samp son's "Old Bob's boat, Folkstone." The lift of the boat as she approaches the shore and the sea are happily caught and naturally rendered. I stood for a long time greatly enjoying the three beautiful water colour drawings of Mr. Beverley. In the "Pier at Newhaven " (No. 759), the bubbling waves to windward of the pier are capitally rendered, and the old timber pier and figures admirable. I turn to "Filey Rocks" and study the whole effect of rocks, sea and atmosphere, is to be reminded truly and forcibly of what that much dreaded portion of the coast is. Mr. E. Hayes's "Genoese craft entering the harbour of Genoa" is altogether pleasing, with the quaint craft. The same must be said of the same gentleman's "Dutch boats on the Scheldt" and "Genoese craft off Venttimiglia." "The approaching storm," by G. A. Williams, is good, but I, as a sailor, should say the storm had already come.