COÖPERATING WITH THE BIRDS THE mere strewing of strings and bits of yarn about the premises, haphazard, so that the birds may find and use them in nest-building, is a practice that I would discourage, because it is not intelligent coöperation with the birds.

For several years a pair of Baltimore orioles built in an elm in the yard of a charitable lady of my acquaintance. One day she, in the kindness of her heart, put out a quantity of yarn for the birds. They were not long in finding it, nor in building a large and many-colored nest. All went happily until the young orioles were well grown, when the nest began to sag, and one day the bottom fell out under the weight of the growing birds, so they fell to the ground and perished. Common white wrapping-twine or any cord equally strong, carpet-thread or stout rope ravelings, in lengths of from two to four feet, and horsehair, are the best material for orioles. The quality of the material for other birds, excepting vireos, is not so important. For robins strips of cloth and pieces of wrapping-twine are best. For house wrens, feathers and horsehair; for treeswallows (who readily build in bird-boxes),

feathers and straw; for warblers, rope ravelings of cotton and hemp, cotton batting, and raw wool; for phoebes, horsehair. The materials should always be placed in a conspicuous position where the wind will move them but not blow them away. Wads of batting may be nailed to a post or a fence; horsehair may be wedged in a splintered post or a fence board or a branch. The stuff should not be placed too near the nest, I should say at least a hundred feet from it.

There are several other birds beside those named above that may be coöperated with in a similar way, but they are not commonly found near home; the king-bird, crested flycatcher, orchard-oriole, and indigo bunting are a few of them. One of the illustrations shows a nest that I helped an indigo bunting to build. The bird started the work in the edge of a brier patch about a hundred feet from my tent. I gathered some wool from the barbed-wire fence of a sheep pasture a mile away, and hung it with a few strips of cloth on a wire fence about fifty yards from the nest. The bird promptly found these, and with them built the most picturesque and artistic bunting's nest that I have ever seen.

the effect noticed but not the cause. If one were to step into a hole in ice, there would be a sudden drop on account of lack of support. So the aviators claim that there are places where the aeroplane drops from lack of air support.

Scientific men prefer not to call these places "holes in the air." Professor Elihu Thomson says that, while this sudden drop may be explained by descending currents of air, such currents are not by any means so serious as the "following gust"-or a wind which increases so fast as to overtake the machine before it can speed up, assuming that the wind blows in the same direction as that of the aëroplane. A suddenly slackening head wind, which has been holding the aviator back, may give rise to effects similar to those of the "following gust." While the descending current does not prevent control, the "following gust" and the "slackening head wind" may destroy all power of control by planes or rudders, and the aviator falls, as the kite does with its string cut. For control of an aeroplane it is absolutely necessary that it be moving fast enough to push upon the air with its planes and rudders. It must go fast enough to produce a strong head wind in the face of the aviator.

When a boy flies a kite, if there is no wind or an insufficient wind, he must run fast so as to get the same effect as if a wind was blowing against the sloping kite surface. When there is a good wind, he need not run, for the wind itself slides under the sloping kite and lifts it. If the string breaks, there is nothing left to hold the kite facing the wind; it turns edgewise, and falls in an irregular course, for it has lost all guidance of any kind. When the engine stops in an aëroplane, there is similar danger, for it is the propeller which pushes the machine against the air, taking the place of the kite-string.

When the engine stops, the aviator is compelled to soar or slide downward in a sloping course, and so maintain as much as possible the headway he has and which the engine, when running, gives him. The "following gust" and "slackening head wind" really deprive him of headway against the air, at least for a time, and put him in imminent danger. If the machine could pick up speed, as fast as the wind can in a

JORDAN'S GOBLIN SHARK

A VERY rare shark, named Scapanorhynchus jordani by the scientists, was discovered in the deep sea, off the coast of Japan. Its curious long "nose," protruding jaws, and small eyes give it an exceedingly grotesque appearance. Its mouth is full of sharp, slender, pointed teeth.

There is only one other species of shark like it, and this also is found off the coast of Japan. In earlier geologic ages, these sharks were quite abundant, as is shown by the frequent finds of their fossil teeth. The largest goblin shark ever caught was eleven feet long; the species probably grows to a length of fifteen feet.

A TEA-SET MADE FROM CODFISH BONES THE photograph here shown is of a tea-set, the pieces of which were made from the vertebræthat is, from the bones that together form the backbone-of a codfish. After they had been boiled, they were flexible and easily molded into any shape. They were then bleached in a solution of lime chloride, which gave them a peculiar appearance, like alabaster. The photograph was sent to us by Miss Florence Meigh, Ash Hall, Stoke-on-Trent, England.

AN INTELLIGENT CHIMPANZEE

"SUSIE," a chimpanzee purchased by the New York Zoological Society, has been attracting much attention at the park. She manifests a great amount of intelligence and some apparently human traits. She sits at the table and eats her meals in a dignified manner, making a fairly good use of fork and cup. It is said by the keepers

that, in a week, apes may be taught to behave at table much like human beings. Susie was obtained in Africa by Professor Richard L. Garner while on a trip there, during which he was engaged in the study of the habits of the gorilla and the chimpanzee. When first captured, she was too young to walk, and was fed on milk and fruit juices. From the very first, her owner sought to teach her how to distinguish geometric forms, such as the cube, cylinder, cone, sphere, square, circle, and rhomb. He also showed that the great apes are not color-blind, because he arranged a series of movable flaps of such colors as green, yellow, blue, and red, and Susie soon learned to lift the different flaps at the word. She also learned to pick out the different geometric forms, and to pick up objects to the number of one, two, or three at command.

THE RAREST LIVING ANIMAL

THIS is a photograph of a part of the rarest kind of animal in the world, rarer, perhaps, than the zebra-like okapi of Central Africa. It is the head

to us. As you have stood by the railroad, you have observed that the farther you look along the track the narrower seems the space between the rails, and the nearer together the rails themselves appear to be. This is a good example of an optical illusion. One of the laws of nature here acts in such a way that our eyes would be deceived, if we did not correct the illusion by an act of our intelligence. We have learned by experience that "seeing is not always believing," and in this case we know that the rails do not come together in the distance.

The little white spot in the photograph is another example of an optical illusion. In the picture, the entrance to the tunnel seems to be 14 inches in width, while the white spot is, perhaps, only the 2 of an inch, yet the spot is the opposite opening of the tunnel, reduced in size by distance, as the result of the law of perspective.

THE HEAD OF A WHITE, SQUARE-MOUTHED RHINOCEROS.

of the gigantic, white, square-mouthed rhinoceros from the Lado district of the Upper Sudan. It was shot, in 1910, by Colonel Roosevelt, and presented by him to the New York Zoological Park, where it is preserved in the Collection of Heads and Horns. It is one of the most noted trophies of Colonel Roosevelt's African hunt.

AN IMPRESSIVE STUDY IN PERSPECTIVE

THIS picture is a photograph of a tunnel for a canal near Paw Paw, West Virginia. This tunnel is 3130 feet long, 27 feet wide, and 221⁄2 feet in height from the ground to the keystone in the arch. When the canal is full, the water is seven feet in depth.

Note the white spot, a little smaller than a pinhead, apparently just above the railing. This is the opening in the other end of the tunnel, and is an astonishing example of what the artist calls diminution by perspective.

The reader is familiar with the fact that the farther away the object is the smaller it looks

A TUNNEL STUDY IN PERSPECTIVE. The white dot is the farther opening of the tunnel.