On the Distribution of Fog round the Coasts of the British Islands.
By Dr. GLADSTONE, F.R.S.

Certain conclusions on this subject formerly arrived at by the author had been re-examined by means of additional returns from the meteorological journals kept at all the stations belonging to the three general lighthouse authorities in England, Scotland, and Ireland, and some returns lent him by Mr. James Glaisher. These afforded confirmation of the greater uniformity of distribution of fogs over the surface of the sea than on land, of their great prevalency where the south-west wind from the ocean strikes upon high ground, of the comparative infrequency of fog on the coasts of straits or portions of sea nearly surrounded by land, and other points previously noted. The returns also indicated that some years are much more foggy than others in nearly all localities; that the same fog sometimes prevails over a large extent of country; and that the frequency of fog differs very greatly in different months of the year, January, February, or March being on some coasts almost free. A generally accepted means of distinguishing between "fog" and "mist” is a great desideratum.

On a New Barometer used in the last Balloon Ascents.
By J. GLAISHER, F.R.S.

Mr. Glaisher exhibited a mercurial barometer which had been designed and constructed by Messrs. Negretti and Zambra for the purpose of checking the readings of the Gay-Lussac's barometer which had been used in the several late balloon ascents. The correctness of the readings of a Gay-Lussac's barometer at low pressure depended upon the evenness of the tube, and it is difficult to calibrate so large a tube. Messrs. Negretti and Zambra selected a good tube, 6 feet in length, attaching a cistern to its lower end. Mercury was boiled throughout the length of the tube; at the entrance of the cistern was placed a stopcock, by which means any definite quantity of mercury could be allowed to pass from the upper half of the tube into the cistern, and its height in the cistern noted and engraved; then a second portion, and so on. This process could be repeated. When the cistern was thus satisfactorily divided, the tube was cut in two, and to the upper half the cistern was joined; a scale was attached to this portion, and the reverse operation was performed, viz., allowing portions of the mercury to pass from the cistern into the tube, which could be regulated by means of the stopcock, and thus the scale was divided. The process, in fact, is using the tube to graduate itself. In carriage, the stopcock locks the mercury in the tube. This instrument was used, and acted well on the extreme high ascent.

On the Additional Evidence of the Indirect Influence of the Moon over the Temperature of the Air, resulting from the Tabulation of Observations taken at Greenwich in 1861-62. By J. PARK HARRISON, M.A.

The author stated that the additional evidence derived from the observations of mean temperature at Greenwich for the years 1861-62 confirmed the conclusions arrived at from a tabulation of the observations for the forty-seven years previous, viz., that the temperature of the air at the moon's first quarter is higher than it is at full moon and last quarter, and that this is due to the amount of cloud at first quarter being greater on the average than it is at the periods of full moon and last quarter. The difference in the amount of rain also at first quarter in 1861-02 was 2-27 inches more than at full moon, on a mean of eighty-four observations on seven days at each period.

On the Relative Amount of Sunshine falling on the Torrid Zone of the Earth. By Professor HENNESSY, F.R.S.

By the aid of the author's transformations of formulæ given by Poisson, the area of that portion of the equatorial regions of the earth which receives as much sunshine as the rest of the earth's surface is ascertained. This area, at the outer limits of the earth's atmosphere, is thus found to be bounded by parallels situate at distances of 23° 44′ 40′′ at each side of the equator; hence the amount of sunshine falling on

the outer limits of the earth's atmosphere between the tropics is very nearly equal to that which falls on the remaining portions of the earth's surface. If we reflect that, according to Principal Forbes's researches, the amount of heat extinguished by the atmosphere before a given solar ray reaches the earth is more than one-half for inclinations less than 25°, and that for inclinations of 5° only the twentieth part of the heat reaches the ground, we immediately see that the torrid zone of the earth must be far more effective than all the rest of the earth's surface as a recipient of solar heat. It follows, therefore, that the distribution of the absorbing and radiating surfaces within the torrid zone must, upon the whole, exercise a predominating influence in modifying general terrestrial climate.

On the Hurricane near Newark of May 7th, 1862, showing the force of the Hailstones and the violence of the Gale. By E. J. Lowe, F.R.A.S. &c. The hurricane about to be described was accompanied by a thunder-storm, which was more or less spread over the centre of England. On the previous evening there were violent thunder-storms, accompanied in various places with large hailstones and with rose-coloured lightning. The hurricane of the 7th of May was remarkable for its violence near Newark, and for the violence of the thunder-storm which occurred at the same time; it will long be remembered in the neighbourhood on account of the devastation that was caused, for the particularly striking night-like darkness, for the great size and curious forms of the hailstones, and on account of the magnificence of the colour of the lightning. At Highfield House the morning was sultry, with thunder about noon, and again continuously in S. and S.E. at three o'clock. At half-past two the temperature in shade had risen to 73°-6 with a west wind, but the clouds whirling round in all directions, a low current carried broken nimbi rapidly from west, whilst the storm-cloud was approaching in a S.S.E. current. At half-past four o'clock the temperature had fallen to 60° (a descent of 13°-6 in two hours), whilst the wind had risen to half a gale. The thunder, though distant, was frequent. The sky gradually became blacker and blacker, until at five o'clock it was darker than I had ever before seen it except during a total eclipse of the sun. A book with bold type could scarcely be read at a window, nor away from it could the hands of a watch be seen. This storm put on very much the appearance of a total eclipse; near objects had a yellow glare cast upon them, and the landscape was closed in on all sides at the distance of half a mile by a storm-cloud wall. Rain fell in torrents, but not in an ordinary manner; it was swept along the ground in clouds like smoke. Flashes of lightning also came in impulses, four or five following each other in rapid succession, succeeded by a brief pause, and then four or five The colour of the lightning was lovely beyond description, being an intense bluish red-almost rose. The wind now veered to the S.S.E., taking the storm's direction. The temperature had descended to 51° (a fall of more than 2210), and the anemometer showed 9 lbs. pressure on the square foot. Severe as this storm was at Highfield House, it dwindled into insignificance when compared with its violence near Newark. It is scarcely possible to imagine any destruction more complete than that effected by this fearful storm. Fortunately its ravages were confined within narrow limits, being restricted to three miles in length and 150 yards in width, commencing at the village of Barnby; after proceeding a mile its violence considerably increased; before reaching Coddington it tore up the hedges that surrounded the fields and unroofed the farm buildings. At Balderton Lane it threw down farm buildings and uprooted enormous oak-trees; a quarter of a mile further it unroofed the house of Mr. James Thorp's head keeper, the hailstones breaking nearly all the windows, having in many instances been driven through the glass, cutting out smooth holes. The spout of this house, too heavy for one man to lift, was carried 100 yards, and a perfectly sound elm-tree, about 60 feet in height and 5 feet 10 inches in circumference (where broken off), was snapped asunder four feet from the ground, and the tree carried twenty-nine yards through the air. The wood of this tree was twisted to the very heart. Here a man was lifted off the ground and then carried twenty yards, being unable to save himself, finally lodging in a hedge. Thirty or forty yards from Mr. Thorp's house at Beaconfield the hurricane divided, leaving the house itself intact, and also the trees in its immediate

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neighbourhood, from S. round by E. to N., while on the W. side outbuildings were unroofed or destroyed, the large garden wall thrown down, and the fencing around the plantations broken off and carried into the fallen timber. A few yards beyond the house the gale reunited, and passing through a wood destroyed all the trees; it then proceeded across fields as far as Winthorpe, and here its fury became exhausted. The gale rotated in the direction of W. to S., which was apparent from the twist of the wood of the snapped-off trees, and also from an avenue of chestnuts situated on the extreme eastern edge of the hurricane having all the torn-off boughs lying on the S. or storm-side, and being carried back beyond the level of the trees.

Proposed Measurement of the Temperatures of Active Volcanic Foci to the greatest attainable Depth, and of the Temperature, state of Saturation, and Velocity of Issue of the Steam and Vapours evolved. By ROBERT MALLET, C.E., M.A., F.R.S.

The author having circulated the following document amongst various Members of the British Association a short time prior to the Meeting and during same, enlarged upon the objects of his proposed experimental inquiry; and explained to Section A, in part, the methods he intended to employ.

Determination of Volcanic Temperatures.—It is a singular fact, and one scarcely creditable to the past investigation of volcanic phenomena, that up to this time no careful attempt has been made to determine, even approximately, the temperature of the heated or incandescent focus of any active volcano, even at the mouth of the crater, still less to depths lower down.

Much labour and time have been lavished upon analysation of the gases and solid products evolved, and upon other still more minute inquiries-more than was necessary, indeed, to obtain all the leading information as to the nature of vulcanicity (using that general term to express the train of forces and of events whence the supply of volcanic heat and energy is kept up) which such results are capable of yielding; but the most obvious of all physical data, viz. those referring to the actual temperature of volcanic foci at the greatest attainable depths, have been completely neglected by vulcanologists, either because they too hastily concluded that experimental measurements of such were impossible, or, more probably, because, as often happens in the investigation of nature, the most obvious question is that which is longest neglected being put to nature.

The experiments that have been made on the heat of lava-fissures, and upon the temperatures of geysers, hot-springs, mines, &c., do not of course bear upon those here in point.

It seems almost unnecessary to dilate upon the importance to vulcanology, and to all cosmical physics, of some precise information as to these focal temperatures, the knowledge of which would assign limits at once to many speculations at present vague and perhaps valueless, give measure to the estimation of the forces concerned, and direct further investigation as to the sources whence these may be derived.

For brevity, the writer may venture to quote on this subject the following passage from his Report to the Royal Society on the great Neapolitan earthquake of 1857 :"I cannot find that any professed investigator of volcanos has ever thought of making the very obvious and important experiment of lowering, with an iron wire, a pyrometer as far as possible into a crater, in order to get some idea of its actuaĺ temperature, even within a few score yards of its mouth.

"When on Vesuvius, on the occasion of this Report, I feel satisfied that I could have so measured the temperature of the minor mouth-then in powerful actionto the depth of several hundred feet, had I possessed the instrumental means at hand. To this smaller mouth it was then possible, by wrapping the face in a wet cloth, to approach so near upon the hard and sharply-defined (though thin and dangerous) crust of lava through which it had broken, as to see its walls for quite 150 feet down, by estimation. They were glowing hot to the very lips, although constantly evolving a torrent of rushing steam with varying velocity. Accustomed as I have been by profession for years to judge of temperature in large furnaces by the eye, I estimated the temperature of this mouth, by the appearance of its heated 1862,

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walls, at the lowest visible depth; they were there of a pretty bright red, visible in bright winter sunlight overhead. I have no doubt then that the temperature of the shaft at from 300 to 500 feet down was sufficient to melt copper, or from 1900°

to 2000° Fahr.

"From the extremely bad conducting power of the walls of a volcanic shaft, there is scarcely any loss of heat from any cause, except its enormous absorption in the latent heat, of the prodigious volume of dry steam, which is constantly being evolved. It is perfectly transparent for several yards above the orifice of the shaft, and is not only perfectly dry steam but also superheated; and although this steam may be at the mouth very much below the highest temperature of the hottest point, the temperature of the shaft or duct that carries it off will be very nearly at all depths the same, to probably within a very short distance of the point of greatest incandescence."-Rep. Roy. Soc., &c., Pt. II. chap. xii. vol. ii. pp. 313, 314.

The writer respectfully urges that the organization of experiments to determine such data is a subject worthy the immediate attention of the British Association, the Royal Society, and other similar scientific bodies.

From recent information he has reason to believe that the existing state of Vesuvius is favourable to such experiments, which the writer is himself prepared to attempt, provided the necessary apparatus and other means be placed at his disposal. The experiments that he would in the first instance propose are—

(1) The temperature at the mouth or mouths, to the lowest reachable depths within the Vesuvian craters.

(2) The temperature of the issuing steam vapours or gases at the mouths, and the degree to which the former are superheated.

(3) Approximate determination of the velocity (extreme and mean) of the issuing discharge of steam, &c., with a view to estimation of the volume, in given time, and of the total heat carried off, in same.

For the 1st and 2nd, three or more mutually controlling methods may be employed. a. The air pyrometer, or that of Daniell, maximum self-registering. b. The differential bar pyrometer (of two metals), with constant galvanic connexion to the surface. c. The resistance coil thermoscope, also in constant connexion with the surface. The writer, as a practical engineer, has well-founded hope of inserting either or all of these to a considerable and known depth within the crater or craters.

For the 3rd, analogous methods should be employed. For the 4th, there is no doubt that Dr. Robinson's anemometer may be so modified as to be made available to determine the issuing velocity in various parts of the column. Into the mechanical arrangements for placing, lowering, and observing, &c. these instruments, it is not necessary here to enter.

Vesuvius presents many advantages as a first experimental station; but the inquiry would afterwards be advantageously extended to other volcanic vents. Whatever presumable difficulties may exist, if successfully overcome in the first case, will nearly vanish as regards subsequent repetitions elsewhere.

On Meteorology, with a Description of Meteorological Instruments.
By T. L. PLANT.

Meteorological Observations registered at Huggate, Yorkshire.
By the Rev. T. RANKIN.

This notice was in continuation of those annually made for many years by the author on the Wolds of Yorkshire, at an elevation of 650 feet above the level of the sea. They contained the annual tables of means, with notes of the days on which the most remarkable events connected with the weather and meteors occurred during the year.

On Objections to the Cyclone Theory of Storms. By S. A. RowELL. Admitting that the winds in storms do at times take a more or less circular course, and that whirlwinds may sometimes occur during storms, the author believed

that these are only occasional and minor phenomena in storms, and not the storm itself, as represented in the cyclone theory. He objected to the cyclone theory on the grounds that it is opposed to all the known natural laws which affect the condition of the atmosphere, as he believed it to be impossible that a disk of some hundreds of miles in diameter, but of a mere mile or so in thickness, of air lighter than the general atmosphere, could make its way for days and days in succession through the densest part of the atmosphere, that the evidence in support of the theory is insufficient (this he attempted to show by the aid of diagrams from Reid's Law of Storms,' and a general reference to works of the kind), and that the phenomena of the (so-called) cyclone storms may be otherwise accounted for.

On the Performance, under trying circumstances, of a very small Aneroid Barometer. By G. J. SYMONS.

This instrument, which the author exhibited, had been worn constantly by him recently while at sea in rough weather, while riding and driving over roadless districts in the Orkneys, and also on several occasions when rough climbing and severe jumps had been necessary: he therefore presumed he might reasonably conclude that it had been fully tried. It had been tested before, during, and after the voyage, and had in each case given the same result when compared with mercurial standards. He therefore inferred that it might be considered even less liable to derangement from travel than an ordinary watch. The instrument was very small, being only two inches in diameter and three-quarters of an inch thick.

On the Disintegration of Stones exposed in Buildings and otherwise to Atmospheric Influence. By Professor JAMES THOMSON, M.A., C.E.

The author having first guarded against being understood as meaning to assign any one single cause for the disintegration of stones in general, gave reasons to show-1st. That there may frequently be observed cases of disintegration which are not referable to a softening or weakening of the stone by the dissolving away or the chemical alteration of portions of itself, but in which the crumbling is to be attributed to a disruptive force possessed by crystalline matter in solidifying itself in pores or cavities from liquid permeating the stone. 2nd. That in the cases in question the crumbling away of the stones, when not such as is caused by the freezing of water in pores, usually occurs in the greatest degree at places to which, by the joint agency of moisture and evaporation, saline substances existing in the stones are brought and left to crystallize. 3rd. That the solidification of crystalline matter in porous stones, whether that be ice formed by freezing from water, or crystals of salts formed from their solutions, usually produces disintegrationnot, as is implied in the views commonly accepted on this subject, by expansion of the total volume of the liquid and crystals jointly, producing a fluid pressure in the pores-but, on the contrary, by a tendency of crystals to increase in size when in contact with a liquid tending to deposit the same crystalline substance in the solid state, even where, to do so, they must push out of their way the porous walls of the cavities in which they are contained, and even though it be from liquid permeating these walls that they receive the materials for their increase.

CHEMISTRY.

Address by Professor W. H. MILLER, M.A., F.R.S., President of the Section. ONCE in about a quarter of a century a mineralogist is placed in the chair of the Chemical Section of the British Association. This procedure is not without its inconvenience: many important questions are likely to present themselves during the meetings of the Section which a mineralogical president can rarely be competent to decide. In another point of view, however, this arrangement is more satisfactory;