be a difficult problem to solve, and then they leave us for a while, until pleasanter weather prevails, when they venture back.

In April, when the chill of winter is no longer in its 5 bones, the robin becomes prominent, and the more so because of the noise it makes. It sings fairly well, and early in the morning there is a world of suggestiveness in the ringing notes. The song is loud, declamatory, and acceptable more for the pleasant thoughts it occasions 10 than for the actual melody. We are always glad to hear the robins, but never for the same reason that we listen to a wood thrush. Of course there are exceptions. With the close of the nesting season and this extends well into the summer much of the attractiveness 15 of the bird disappears. As individual members of great loose flocks that fret the upper air with an incessant chirping, they offer little to entertain us even when the less hardy minstrels of the summer have sought their southern homes.

20 It is true that they add something to the picture of a dreamy October afternoon when the mellow sunlight tips the wilted grasses with dull gold. They restore for the time the summertide activity of the meadows when with golden-winged woodpeckers they chase the crickets in the 25 close-cropped pastures, but they are soon forgotten if a song sparrow sings or a wary hawk screams among the clouds. Robins are always welcome, but never more so than when they chatter, on an April morning, of the near future with its buds and blossoms.

— From "Bird-Land Echoes," by Charles Conrad Abbott.

THE MOTIONS OF BIRDS.

A good ornithologist should be able to distinguish birds by their air as well as by their colors and shape, on the wing as well as on the ground; and in the bush as well as in the hand. For though it must not be said that every species of bird has a manner peculiar to itself, yet 5 there is somewhat in most genera, at least, that at first sight discriminates them, and enables a judicious observer to pronounce upon them with some certainty.

Thus kites and buzzards sail round in circles with wings expanded and motionless; and it is from their glid- 10 ing manner that the former are still called in the north of England gleads, from the Saxon verb glidan, to glide. Hen harriers fly low over the meadows or fields of corn, and beat the ground regularly like a pointer or setting dog. Owls move in a buoyant manner, as if lighter than 15 the air; they seem to want ballast.

There is a peculiarity belonging to ravens that must draw the attention even of the most incurious — they spend all their leisure time in striking and cuffing each other on the wing in a kind of playful skirmish; and, 20 when they move from one place to another, frequently turn on their backs with a loud croak, and seem to be falling to the ground. When this odd gesture betides them, they are scratching themselves with one foot, and thus lose the center of gravity. Rooks sometimes dive 25 and tumble in a frolicsome manner; crows and daws swagger in their walk; woodpeckers fly with a wavy motion, opening and closing their wings at every stroke,

and so are always rising or falling in curves. All of this genus use their tails, which incline downward, as a support while they run up trees. Parrots, like all other hooked-clawed birds, walk awkwardly, and make use of 5 their bill as a third foot, climbing and descending with ridiculous caution.

All the gallinæ parade and walk gracefully, and run nimbly, but fly with difficulty, with an impetuous whirring, and in a straight line. Magpies and jays flutter 10 with powerless wings, and make no dispatch; herons seem encumbered with too much sail for their light bodies, but these vast hollow wings are necessary in carrying burdens, such as large fishes, and the like; pigeons, and particularly the sort called smiters, have a 15 way of clashing their wings, the one against the other, over their backs with a loud snap; another variety, called tumblers, turn themselves over in the air.

The kingfisher darts along like an arrow; fern owls, or goatsuckers, glance in the dusk over the tops of trees 20 like a meteor; swallows sweep over the surface of the ground and water, and distinguish themselves by rapid turns and quick evolutions; swifts dash round in circles; and the bank martin moves with frequent vacillations like a butterfly.

25

Most small birds hop; but wagtails and larks walk, moving their legs alternately. All the duck kind waddle; divers and auks walk as if fettered, and stand erect, on their tails. Geese and cranes, and most wild fowls, move in figured flights, often changing their position.

From "The Natural History of Selbourne," by Gilbert White.

THE ORIGIN OF RIVERS.

Let us trace a river to its source. Beginning where it empties itself into the sea, and following it backwards, we find it from time to time joined by tributaries which swell its waters. The river of course becomes smaller as these tributaries are passed. It shrinks first to a brook, 5 then to a stream; this again divides

John Tyndall.

of the rivers.

itself into a number of smaller streamlets, ending in mere threads of water. These constitute the source of the river, and are usually found 10 among hills.

Thus, the Severn has its source in the Welsh mountains; the Thames in the Cotswold Hills; the Missouri in the Rocky Moun- 15 tains; and the Amazon in the Andes of Peru.

But it is quite plain that we have not yet reached the real beginning

Whence do the earliest streams derive 20 their water? A brief residence among the mountains would prove to you that they are fed by rains. In dry weather you would find the streams feeble, sometimes, indeed. quite dried up. In wet weather you would see them foaming torrents. In general these streams lose 25 themselves as little threads of water upon the hillsides; but sometimes you may trace a river to a definite spring. But you very soon assure yourself that such springs are

also fed by rain, which has percolated through the rocks or soil, and which, through some orifice that it has found or formed, comes to the light of day.

But we can not end here. Whence comes the rain that 5 forms the mountain streams? Observation enables you to answer the question. Rain does not come from a clear sky. It comes from clouds.

But what are clouds? Is there nothing you are acquainted with which they resemble? You discover at 10 once a likeness between them and the condensed steam of a locomotive. At every puff of the engine a cloud is projected into the air.

Watch the cloud sharply. You notice that it first forms at a little distance from the top of the funnel. 15 Give close attention and you will sometimes see a perfectly clear space between the funnel and the cloud. Through that clear space the thing which makes the cloud must pass. What then is this thing which at one. moment is transparent and invisible, and at the next 20 moment visible as a dense opaque cloud?

It is the steam or vapor of water from the boiler. Within the boiler this steam is transparent and invisible e; but to keep it in this invisible state a heat would be required as great as that within the boiler. When the 25 vapor mingles with the cold air above the hot funnel, it ceases to be vapor. Every bit of steam shrinks, when chilled, to a much more minute particle of water. The liquid particles thus produced form a kind of water dust of exceeding fineness, which floats in the air, and is called 30 a cloud.