European area of low pressure has not materially altered, the cyclones which lie within it have decreased in complexity, though a new depression has formed in a col between the Azores and the Canaries. The two American secondaries have fused into one large primary, and a large col covers the Central Atlantic.

Lastly, on the 28th (Fig. 79), while the Scandinavian anticyclone has diminished in height and area, the Atlantic anticyclone, on the contrary, has increased no less than 0.4 inch (10 mm.) in height, and much increased in size. The size and intensity of the European low pressure has diminished, but its components are more complex; so

that while weather has improved over Great Britain, it is worse in many parts of France and Italy. Across the Atlantic, all we can say is that where one large cyclone was yesterday, there are now two secondaries: one intense over Nova Scotia, another slight in the Atlantic col. This is one of the numerous cases where it is impossible to trace the exact history of pressure-changes.

The general character of the weather in Great Britain during the persistence of this type is very well marked. The sky is usually black, and, even if there is a certain amount of blue overhead, the horizon has a peculiar black, misty look, popularly known as an "eastern haze." This is quite different from the misty horizon of a calm day in the westerly type, and is associated with the peculiar bitter feel of an east wind. A well-known saying is

"When the wind is in the east,

It's good for neither man nor beast; and this is certainly no exaggeration.

This is the most striking illustration we can have of the general principle that no instrumental records can take the place of verbal description. We might find two north-east winds recorded automatically, of exactly the same velocity and temperature-one on the northern side of a cyclone of the westerly type, the other at the edge of the Scandinavian anticyclone in the easterly type. Read mechanically, they might be taken to be identical, while practically they are very different. Unfortunately we can give no explanation of the malignant nature of true east winds.

The temperature is generally low, but more variable

than during the northerly type. This is because the cyclone-centres sometimes get so far east as to bring up a breath of southerly wind, which is speedily driven back by a new irruption of pressure from Scandinavia.

The wind is always from some point of east, with less tendency to back towards the north than during the continuance of the northerly type, and generally keeping between north-east and south-east. The contrast between this and the westerly type will be strikingly evident if we look back at Figs. 71-73, and note that they refer to the same three days of the year, February 26-28, as our last three (Figs. 77-79). By selecting these dates on different years, all diurnal and seasonal variations are equalized, and the entire difference of wind and weather is solely due to difference of type.

Forecasting during the persistence of this type presents the greatest difficulties, especially in ̧ Western Europe. Though the general character of the weathersequence may be sufficiently obvious, still there is the utmost uncertainty as to the paths of cyclones. When these come in from the Atlantic, we have no means of saying whether they will pass through the col in a southeasterly direction, or whether they will be deflected to a north-easterly course. In addition to this, the motion of cyclones, in whatever direction, is so irregular that the forecaster is doomed to frequent failure.

The signs of persistence are chiefly such as may be derived from watching the position of the Scandinavian anticyclones, and the continuance of low pressure to the west of Ireland. The signs of change, on the contrary, turn round any diminution of pressure in Sweden,

or the appearance of high pressure far north in the Atlantic.

The four great types of weather which we have now sketched are capable of being divided more minutely into sub-types; but these would vary so much for different countries, that they cannot be detailed in this work. All that we can do here is to note the universality of the principle, and the properties of weather which the existence of types explains so readily.

Although we have already mentioned the great principles of weather-changes which are designated by the terms "intensity," "fluctuation," "persistence," "recurrence," and "dependence" of type more or less incidentally, it may be well to add a few remarks here on all of them, beginning with

INTENSITY.

We have already explained the term "intensity" as applied to single cyclones, and shown both how it is measured by the gradients and how it influences the weather.

But "intensity of type" denotes the character of a sequence of weather to which the epithet of "broken" would be applied. Broken weather is found by synoptic charts to be the product either of small quick-moving cyclones which only exist for a very short time, or of numerous secondaries; in contradistinction to the weather produced by large low-gradient cyclones, moving slowly and lasting for some days, which would be associated with more settled weather.

The relation between these two kinds of intensity is analogous to that between long, single, heavy gusts, and numerous short puffs of wind; both are symptoms of great atmospheric disturbance, though of a different kind in each case.

FLUCTUATION.

The word "fluctuation" is applied to that limited alternation of a general distribution of pressure which occurs every day all over the world. In the tropics, where pressure-distribution is unchanged for months, fluctuation is chiefly confined to small modifications of intensity, which make the weather a little better or a little worse, according to circumstances. In semi-tropical countries fluctuation is much larger, usually from the formation of secondaries, though the general type does not materially change. In the temperate zone, on the contrary, we have not only enormous fluctuation of type, but also complete alteration of the type itself. The classification of phenomena called fluctuation is of the greatest value in handling questions of weather-sequence, as it enables us to separate that which is incidental from that which is essential to any type.

PERSISTENCE.

The word "persistence" describes that prominent feature of remaining pretty stationary which characterizes all pressure-distribution over large areas. This is always concurrent with a persistence of appropriate