Meteorological Office. Attention has been drawn in the previous half-yearly Reports of the Council to the totally diverse distribution of rains with easterly winds and westerly winds respectively; and also to the direction of the wind at the top of Ben Nevis compared with the winds at sea-level at the same time, as giving an indication of the depth of the barometric depression and extent of a coming cyclone. Now, it is on these lines that the problem of forecasting rains, more particularly the geographical distribution of very heavy rains, is being prosecuted.

A discussion of the two sets of observations at the two observatories in their bearings on the storms and weather of North-western Europe has been in progress for some time. The following is a sketch of the method adopted :-The subject is divided into these several parts-cyclones; anti-cyclones; unusually small differences of temperature between top and bottom, including inversions of temperature; large differences of temperature; great dryness of air at the top; marked differences of wind at top and bottom, either as regards direction or force; the rainfall above and below; relations to storms reported at the lighthouses; conditions under which very diverse readings of the two barometers occur. In each of these cases the Daily Weather Charts and the Weather Charts of Europe at the time are examined. Thus, for example, in dealing with cyclones, the following data are entered in the columns of the sheet for the investigation of cyclones: the position in Europe of the cyclone; position of the nearest anti-cyclone at the time, with its highest barometer; the direction, whether N., N.E., E., &c., Ben Nevis is from the cyclone; its distance from the centre of the cyclone in miles; the temperatures at the observatories; the humidities at ditto; the sunshine and cloud; the barometer at sea-level at Ben Nevis, with lowest barometer at centre of cyclone, and its position; wind at sea-level and top of mountain; storms at lighthouses; and the distribution of rainfall over Scotland.

It will be observed that there is in all this work an unmistakable recognition of the fact that the problem of the weather is an excessively difficult one, and that the method adopted in dealing with it is solely through the facts of observations made at numerous stations, well distributed over Scotland, at sea-coast and inland situations, and at various heights up to 4,406 feet.

Part II.-Life and Observing at the Ben Nevis Observatory. By R. T. OMOND, F.R.S. E., Superintendent.

WHEN the Observatory on the summit of Ben Nevis was built, it was resolved by the Directors that it should be a meteorological station of the first class-that is to say, one whose records should give hourly values of the barometer, temperature, wind, rainfall, cloud, and sunshine. All mountain observatories previous to that time had been second-class stations, at which observations of these data were made only at certain fixed hours each day, helped, in some cases, by tracings of such self-registering instruments as could be used in these isolated situations. The first winter's experience on Ben Nevis showed that a continuous record could only be got by direct eye observations at each hour, as no self-recording instruments of sufficient delicacy to give the wind, temperature, humidity, and rainfall accurately could be trusted to work in such a climate; and, since May, 1884, hourly readings by day and night have been taken. The following are the arrangements by which this became possible :

(1) Buildings. To the original oblong hut that was erected in 1883 there was added in 1884 an extension, consisting mainly of an office-room and a tower. The former made it possible to tabulate the observations and do computing work in a far more complete and satisfactory manner than formerly, while the latter served many purposes. A door near the top allows the observers ready communication in and out when the main building is buried in snow; on the roof anemometers are placed, and the upper storey, which has windows all round, makes a convenient outlook under cover.

(2) Instruments.-The thermometers are exposed in doublelouvred screens (slightly smaller than the ordinary Stevenson screen), which are kept at approximately the standard height of four feet above ground by being attached to upright stands shaped like ladders, on the successive steps of which the screen can rest. Duplicate screens and instruments are in use, so that when one set become choked with snow, they can be removed bodily and replaced by a fresh set. Duplicate rain or snow gauges are also used. These are cylindrical in shape, widening out below into a

rounded base, so as to be easily levelled when resting on snow. One is taken out each hour, the previous one containing the hour's fall being brought in and measured at leisure inside. The wind is estimated in direction and pressure by the observer when out, his values being checked by the readings of an anemometer when the weather allows.

(3) Personal.-All these arrangements, it will be seen, necessitate the presence of an observer at each hourly reading. There are, therefore, two men engaged in this work. The day is divided into watches, eight hours long at night and four hours during the day, so that each observer has twelve hours' duty out of the twenty-four. The actual observation only takes about five or ten minutes, but during the remainder of the time there is plenty to do in entering up observations, averaging the previous day's records, and preparing the monthly tabulations and summaries.

This steady routine of hourly observations has gone on now for nearly twelve years without a break, except on one or two occasions, when, for a few hours, wind and snowdrift rendered it impossible to stand or to see the thermometers outside. Any ordinary gale can be faced if the observer is protected by oilskins, and at night keeps his lantern to leeward of him while he feels his way along the guide-rope stretched from the door to the instrument stands; but when the wind rises above 100 miles per hour, carrying with it drift torn up from the snow lying on the hill-sides, sufficiently solid to break a plate-glass window when dashed against it, it is useless to attempt any out-door observing. A storm of this sort may be expected about every second or third winter, and, in order to secure continuity in the temperature record, arrangements have been made whereby a louvred screen can be placed on the wall of the tower, and the thermometers in it read from within. Experience has shown that this method gives temperature values practically identical with those of the ordinary screens in stormy weather, though on calm and sunny days the thermometers would get unduly heated by the near presence of the tower wall. Under ordinary circumstances, one observer is on duty from 8 p.m. to 4 a.m.; he then wakens the other, who has had this time for sleep, and goes to bed himself; the second observer is on duty till noon, and then both are at work in the afternoon. By this system of work not only are the observations recorded as they go on, but they are reduced, tabulated, averaged, and put in

a form suitable for further investigations by the same persons who take them. Several members of the staff have found time to carry out discussions of the results so obtained, most of which work will be found in the publications of the Royal Society of Edinburgh and of the Scottish Meteorological Society.

Taking an average over the year, the summit of Ben Nevis is in mist for two days out of every three, for only one-third of the time is the hill-top clear. The mist varies much in character: sometimes it is thin, but intensely wetting; at other times it is much thicker, reducing the visible world to a few square yards, but comparatively dry. The wetter forms are classified as mists, and the drier as fogs, but no exact distinction can be drawn, as the degrees of dampness vary insensibly from what soaks worse than heavy rain, because more penetrating, to what seems to render the atmosphere opaque without wetting things exposed to it. As long as the air temperature is above freezing, little inconvenience is caused by either fogs or mists, which are interesting meteorological phenomena, but that is all; in frost, however, they become serious drawbacks to accurate observing, for it is no longer moisture that is deposited upon them, but hard, solid ice out of a mist, and masses of loose, feathery crystals from a fog. These form on the windward side of everything that the air touches, and the fog-crystals in a strong wind and thick fog may grow at the rate of two feet per day, though not a particle of snow be falling. No selfregistering instruments that had to be left to themselves for many hours at a time would work under such conditions; it is necessary that personal inspection of the thermometers should be made at least once an hour, the fog-crystals cleared away, or, if necessary, the whole screen removed and another put out. Mist is even a worse enemy in the winter, as the moisture from it turns at once into ice, and frequently rain falls at the same time, freezing as it touches the snow, and rapidly covering everything with a thick layer of hard ice. This ice cannot be knocked off posts, screens, &c., like the fog-crystals, and it adds greatly to the labour of shifting the thermometer screens, and keeping things in order generally. Fortunately, mist is rare, even rarer than fine weather; fog is the normal condition in winter.

The finest weather of the year on Ben Nevis, as in the Northwest Highlands generally, is in spring and early summer. From March to June every year there are long spells of dry, sunny weather, such as never occur in autumn, and the observers are

able both to do more outside work and to enjoy the pleasures of tobogganing, snow-shoe tramps, and other semi-arctic sports. The pleasures of flying down the hill-side on a toboggan are heightened by the knowledge that, if guided wrongly, or allowed to run too far, the course may end in a precipice or some such obstacle. But, with fair care, a great amount of good sport can be obtained, the latest addition to the stock of amusements being Norwegian snowshoes, or "skier," on which the novice learns speedily to slide down hill, but finds it impossible to do anything else, even to stop, without a tumble.

The view on a clear day extends from Ben Wyvis in the north to the coast of Ireland, and from the Outer Hebrides to the Cairngorm Mountains; but a feature of the view is that no town or village of more than two or three houses can be seen, except a few of the outlying buildings of Inverness. Many populous places lie within this range. Fort-William and Oban are quite near; Glasgow, Paisley, Greenock, and Stirling are no further away than the Island of Jura, which is visible any moderately clear day; yet none of these places can be seen, they are all hid by intermediate hills; indeed, the aspect of the country is all hills, the valleys where men live disappear, and nothing can be seen but ridge behind ridge of barren mountains. Almost the only open space in sight is the Moor of Rannoch, that central wilderness of Scotland. But the view is saved from monotony by the abundance of water. The Atlantic Ocean forms the western horizon, and Loch Linnhe, with its broken and winding coastlines, spreads out from just below the spectator's feet, while every here and there fresh-water lochs and tarns gleam out amongst the hills.

Snow seems to lie on Ben Nevis longer than on any of the other hill-tops near, due, doubtless, to its flatness. The summit is rather an elevated plateau than a ridge or cone, and the snow gets better opportunity to accumulate than on a narrow ridge. Strangers coming up in early summer often express surprise at finding snow lying on a warm day exposed to a blazing sun, and it is difficult to convince them that it is melting away as fast as it can, and that it is only the great quantity which falls in winter that enables it to last so long through weeks of thaw. May is generally the first month in which there is a distinat melting away of the winter snow, and April, therefore, is the month in which it reaches its maximum depth. While the snow is falling