eave-swallow, to which I have chiefly alluded, and the chimney-swallow, there is the swift, also a roof-bird, and making its nest in the slates of houses in the midst of towns. These three are migrants in the fullest sense, and come to our houses over thousands of miles of land and sea.

Robins frequently visit the roof for insects, especially when it is thatched; so do wrens; and the latter, after they have peered along, have a habit of perching at the extreme angle of a gable, or the extreme edge of a corner, and uttering their song. Finches occasionally fly up to the roofs of country-houses if shrubberies are near, also in pursuit of insects; but they are not truly roof-birds. Wagtails perch on roofs; they often have their nests in the ivy, or creepers trained against walls; they are quite at home, and are frequently seen on the ridges of farmhouses. Tits of several species, particularly the great titmouse and the blue tit, come to thatch for insects, both in summer and winter. In some districts where they are common, it is not unusual to see a goatsucker or fern-owl hawk along close to the eaves in the dusk of the evening for moths. The white owl is a roof-bird (though not often of the house), building inside the roof, and sitting there all day in some shaded corner. They do sometimes take up their residence in the roofs of outhouses attached to dwellings, but not often nowadays, though still residing in the roofs of old castles. Jackdaws, again, are roof-birds, building in the roofs of towers. Bats live in roofs, and hang there wrapped up in their membranous wings till the evening calls them forth. They are residents in

the full sense, remaining all the year round, though principally seen in the warmer months; but they are there in the colder, hidden away, and if the temperature rises, will venture out and hawk to and fro in the midst of the winter. Tame pigeons and doves hardly come into this paper, but still it is their habit to use roofs as tree-tops. Rats and mice creep through the crevices of roofs, and in old country-houses hold a sort of nightly carnival, racing to and fro under the roof. Weasels sometimes follow them indoors and up to their roof strongholds.

When the first warm rays of spring sunshine strike against the southern side of the chimney, sparrows perch there and enjoy it; and again in autumn, when the general warmth of the atmosphere is declining, they still find a little pleasant heat there. They make use of the radiation of heat, as the gardener does who trains his fruit-trees to a wall. Before the autumn has thinned the leaves, the swallows gather on the highest ridge of the roof in a row and twitter to each other; they know the time is approaching when they must depart for another climate. In winter, many birds seek the thatched roofs to roost. Wrens, tits, and even blackbirds roost in the holes left by sparrows or starlings.

Every crevice is the home of insects, or used by them for the deposit of their eggs-under the tiles or slates, where mortar has dropped out between the bricks, in the holes of thatch, and on the straws. The number of insects that frequent a large roof must be very great-all the robins, wrens, bats, and so on, can scarcely affect them; nor the spiders, though

these, too, are numerous. Then there are the moths, and those creeping creatures that work out of sight, boring their way through the rafters and beams. Sometimes a sparrow may be seen clinging to the bare wall of the house; tits do the same thing. It is surprising how they manage to hold on. They are taking insects from the apertures of the mortar. Where the slates slope to the south, the sunshine soon heats them, and passing butterflies alight on the warm surface, and spread out their wings, as if hovering over the heat. Flies are attracted in crowds sometimes to heated slates and tiles, and wasps will occasionally pause there. Wasps are addicted to haunting houses, and, in the autumn, feed on the flies. Floating germs. carried by the air must necessarily lodge in numbers against roofs; so do dust and invisible particles; and together, these make the rain-water collected in water-butts after a storm turbid and dark; and it soon becomes full of living organisms.

Lichen and moss grow on the mortar wherever it has become slightly disintegrated; and if any mould, however minute, by any means accumulates between the slates, there, too, they spring up, and even on the slates themselves. Tiles are often coloured yellow by such growths. On some old roofs, which have decayed, and upon which detritus has accumulated, wallflowers may be found; and the house-leek takes capricious root where it fancies. The stonecrop is the finest of roof-plants, sometimes forming a broad patch of brilliant yellow. Birds carry up seeds and grains, and these germinate in moist thatch. Groundsel, for instance, and stray stalks of wheat,

thin and drooping for lack of soil, are sometimes seen there, besides grasses. Ivy is familiar as a roofcreeper. Some ferns and the pennywort will grow on the wall close to the roof. A correspondent tells me that in Wales he found a cottage perfectly roofed with fern-it grew so thickly as to conceal the roof. Had a painter put this in a picture, many would have exclaimed: "How fanciful! He must have made it up; it could never have grown like that!" Not long after receiving my correspondent's kind letter, I chanced to find a roof near London upon which the same fern was growing in lines along the tiles. It grew plentifully, but was not in so flourishing a condition as that found in Wales. Painters are sometimes accused of calling upon their imagination. when they are really depicting fact, for the ways of nature vary very much in different localities, and that which may seem impossible in one place is common enough in another.

Where will not ferns grow? We saw one attached to the under-side of a glass coal-hole cover; its green could be seen through the thick glass on which people stepped daily.

Recently, much attention has been paid to the dust which is found on roofs and ledges at great heights. This meteoric dust, as it is called, consists of minute particles of iron, which are thought to fall from the highest part of the atmosphere, or possibly to be attracted to the earth from space. Lightning usually strikes the roof. The whole subject of lightningconductors has been re-opened of late years, there being reason to think that mistakes have been made

in the manner of their erection. The reason English roofs are high-pitched is not only because of the rain, that it may shoot off quickly, but on account of snow. Once now and then there comes a snow-year, and those who live in houses with flat surfaces anywhere on the roof soon discover how inconvenient they are. The snow is sure to find its way through, damaging ceilings, and doing other mischief. Sometimes, in fine summer weather, people remark how pleasant it would be if the roof were flat, so that it could be used as a terrace, as it is in warmer climates. But the fact is, the English roof, although now merely copied and repeated without a thought of the reason of its shape, grew up from experience of severe winters. Of old, great care and ingenuity-what we should now call artistic skill-were employed in constructing the roof. It was not only pleasant to the eye with its gables, but the woodwork was wonderfully well done. Such roofs may still be seen on ancient mansions, having endured for centuries. They are splendid pieces of workmanship, and seen from afar among foliage, are admired by every one who has the least taste. Draughtsmen and painters value them highly. No matter whether reproduced on a large canvas or in a little woodcut, their proportions please. The roof is much neglected in modern houses; it is either conventional, or it is full indeed of gables, but gables that do not agree, as it were, with each other -that are obviously put there on purpose to look artistic, and fail altogether. Now, the ancient roofs were true works of art, consistent, and yet each varied to its particular circumstances, and each impressed