When the condors are wheeling in a flock round and round any spot, their flight is beautiful.  Except when rising from the ground, I do not recollect ever having seen one of these birds flap its wings.  Near Lima, I watched several for nearly half an hour, without once taking off my eyes; they moved in large curves, sweeping in circles, descending and ascending without giving a single flap.  As they glided close over my head, I intently watched from an oblique position, the outlines of the separate and great terminal feathers of each wing; and these separate feathers, if there had been the least vibratory movement, would have appeared as if blended together; for they were seen distinct against the blue sky.  The head and neck were moved frequently, and apparently with force; and the extended wings seemed to form the fulcrum on which the movements of the neck, body, and tail acted.  If the bird wished to descend, the wings were for a moment collapsed; and when again expanded with an altered inclination, the momentum gained by the rapid descent seemed to urge the bird upwards with the even and steady movement of a paper kite.  In the case of any bird soaring, its motion must be sufficiently rapid, so that the action of the inclined surface of its body on the atmosphere may counterbalance its gravity.  The force to keep up the momentum of a body moving in a horizontal plane in the air (in which there is so little friction) cannot be great, and this force is all that is wanted.  The movement of the neck and body of the condor, we must suppose, is sufficient for this.  However this may be, it is truly wonderful and beautiful to see so great a horde, hour after hour, without any apparent exertion, wheeling and gliding over mountain and river.

[Illustration]

THE UMBRELLA BIRD

(FROM TRAVELS ON THE AMAZON.)

BY SIR A. R. WALLACE.

[Illustration]

This singular bird is about the size of a raven, and is of a similar color, but its feathers have a more scaly appearance, from being margined with a different shade of glossy blue.  It is also allied to the crows in its structure, being very similar to them in its feet and bill.  On its head it bears a crest, different from that of any other bird.  It is formed of feathers more than two inches long, very thickly set, and with hairy plumes curving over at the end.  These can be laid back so as to be hardly visible, or can be erected and spread out on every side, forming a hemi-spherical, or rather a hemi-ellipsoidal dome, completely covering the head, and even reaching beyond the point of the beak:  the individual feathers then stand out something like the down-bearing seeds of the dandelion.  Besides this, there is another ornamental appendage on the breast, formed by a fleshy tubercle, as thick as a quill and an inch and a half long, which hangs down from the neck, and is thickly covered with glossy feathers, forming a