In summer when our climate is nearer in heat to that of the tropics, the air rushes to us with less force and velocity.

This tendency of the air to preserve an equilibrium is one of the wisest laws of creation, for by it the northern regions are warmed by the hot air from the torrid zone, and the torrid zone air is cooled by the cold air from the poles. In addition to this, the air from the tropics, where great portions of land are covered with vast forests, is full of oxygen, while in the temperate and polar regions, fires and congregated human beings fill the air with carbonic acid. The mingling of the hot and cold atmospheres is consequently beneficial to both. The polar air currents carry carbonic acid to the plants of the torrid zone, while the equatorial currents carry oxygen to the animals of the other zones.

The west winds coming across the Atlantic are laden with vapour, and on meeting with the least chill fall in rain. East winds cross the cold plains of the north of Europe, and as they pass chiefly over land do not absorb much water; they are consequently very dry and absorb moisture from our air and clouds.

The north wind is generally cold, keen, and dry, because it comes from the Arctic Regions, over mountains of snow and plains of ice, and being warmed by the heat of our island instantly absorbs all the moisture it can find. The north-east wind from the same causes is also a dry one. South winds are warm because they come to us over the scorching sands of Africa, and consequently imbibe water in large quantities as they cross the Mediterranean and English Channel; as soon as they react our colder climate they are condensed - can no longer hold their vapour in solution - and it falls as rain.

* Petrelli, or little Peters, so called from the manner in which they walk or run on the top of the waves.

Sea breezes are very salubrious, both on account of the constituent elements of the sea air, and because they are not laden with noxious vapours; this is especially the case in the morning, when the cool air from the sea, which has never been heated as the land breeze has, creeps inland to restore the equilibrium of the air by pressing the light hot air upwards.

Land breezes are coolest of an evening because the surface of the land cools down after sunset more quickly than the surface of the sea, therefore the air from the land feels cooler than that from the sea. Islands are warmer in winter than continents, because the warmth of the sea air mitigates the cold of the land air.

Dew is condensed vapour from the air. It is condensed by coming in contact with bodies colder than itself. In summer there is much dew because the hot earth radiates or throws off heat freely and the air does not; consequently after sunset the earth is often many degrees colder than the air, and the warm vapour of the air which touches it is chilled and condensed into dew. Clouds arrest the radiation of heat from the earth, consequently on dull cloudy evenings and nights there is no dew. In consequence of the clouds preventing the radiation of heat from the earth, the surface of the ground retains its warmth and a cloudy night becomes closer and hotter than a fine clear one. Any covering prevents the radiation of heat from the earth, therefore if an awning be spread out of doors there will be little or no dew under it, even if it should be open at the sides. It is a knowledge of this principle which enables us to protect trees from the frost. Any covering prevents the radiation of heat from the tree; and if trees are not cooled down by radiation the air-vapour will not be frozen when it comes in contact with them. A thin covering: of muslin is there-fore sufficient to prevent them from being struck by the frost.

But the bass or canvas usually employed to cover fruit trees is always drenched with dew itself, because it radiates heat both upwards and downwards, and in consequence is so cooled that it readily condenses the air-vapour into dew.

Leaves of plants and grass radiate heat very freely, and by doing so condense the vapour of the air into dew very easily; thus they supply their great need of moisture in dry weather.

Polished metal and smooth stones do not radiate heat well, and consequently scarcely get any dew by condensing the air-vapour. Thus only the things which require dew, make it.

Radiation is carried on very rapidly on bright moonlight nights; dew is consequently largely deposited on young plants and trees, and thus their growth is promoted.

Evening clew is always laden with exhalations from the earth which are injurious to health; it should therefore be avoided.

There are certain small weather-toys which admirably supply the place of the barometer where the expense of the latter prevents purchasing it. The capuchin is one; in this the monk's cowl is on when rain is coming, but is taken off when it is fine. This is caused by the catgut which is attached to it; being shortened by moisture it pulls the cowl up. In dry weather the string expands and the cowl falls by its own weight. In the other toys, where a man and a lady, or a knight and a jester, etc., come out alternately, the same principle acts; the moist catgut sending out the man, or knight, as it may be.