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BIRDS AS AVIATORS' MODELS
sorb its energy.
mechanism of the flight by sailing and in There results in these birds a sort of particular this paradoxical fact that the balancing very clearly noticeable to bird can rise and make headway against observers. This balancing is very much the wind.
diminshed in large sailing birds with Many explanations have been pro- supple wings; the shifting of the wings posed, some fantastic, others the discus- comes into play and as the total miass of sion of which leads to such absurd deduc- the body and of the wings requires much tions as the realization of perpetual greater energy in order to be displaced motion; others again, true perhaps in from its equilibrium, it is the wings alone certain particular cases, could not be that feel the effect of the changes of the embraced in a general theory. To this direction of the wind. And when the last class belong the hypotheses based on variations of the wind are very slight, the utilization of the ascendant currents the feathers alone, the respective indeand on the variations of the velocity of pendence of which makes them like so the wind. It is cer
many small wings tain that the bird
for independent gains in the ascend
shifting, receive the ing currents of the
puff of air and abair; but there have been noted also
The large sailing many sailing flights
birds having to count with the wind hori
only upon the wind zontal or even de
are necessarily conscending; so that if
to the theory of the
utilize the lightest ascendant wind suits
breath of air ; everyvery well certain
thing with them cases, as also that
tends to this result, which utilizes the
from the sensitivevariations of velocity
ness of the feathers and direction of the
and the suppleness of wind, there remains
the wing, to the abilto be found a gen
ity of spreading the eral theory which
wing like a fan may be applied to all
when, if they wish these different cases. Fig, 10. VULTURE SOARING.
to rise, they have The sailing bird,
need to increase having only the aid of the wind to sup- their sail. This explains the different port it in the air, must be built for positions reproduced in our figures 4 and utilizing the slightest current of air from 8, the first corresponding to a light wind whatever direction it comes. It is neces- for the utilization of which it is necessary sary also that its organs be delicate to set full sail, the other becoming necesenough to adapt it without delay to the sary when the wind freshens and there changes of the direction of the wind is need of taking a reef. Between these which are almost always very sudden. two extreme cases, there is an infinity These results are assured by the supple- of intermediate situations that the shiftness of the wings themselves and by that ing of the feathers, or that of the wings, of the feathers, since the position of the if it is necessary, suffice to regulate. The plane to the air has to be modified. In quill-feathers, in fact, constitute an autofact each change of direction of the wind matic shifting device which assures the requires, if the wings are not sufficiently longitudinal and lateral equilibrium in supple, an oscillation of the body and of normal conditions; the assistance of the the wings all together. This is what is wing, and of the entire body, are used produced in the semi-sailing birds with only in extremely violent strokes. This the wings relatively rigid, the tips of automatic shifting is indispensable to which are convex and predominant as in birds that practice flight by sailing, and the case of the sea gull and swallow. those which are not provided with it, the semi-sailers, are not as good Ayers in utilize them according to circumstances. high winds, unless they spread their It is then the semi-sailers much more wings like a fan as the stork in figure than the sailers that practice the most nine, in order to give a little independ- perfect flight, and man's imitation, which ence to the extremities of the feathers. is often a criterion, gives actual proof But this slight defect is not sufficient to of this. The aeroplane as it is conceived destroy the brilliant qualities of flight today, is only a semi-sailer with its screw which these birds present; powerful propeller which allows it to take fight rowers, they are masters of the air, not and sustain itself in the air, with its supbeing, like the large sailing birds, at the porting and shifting planes, and its rudmercy of a dead calm, which is always der which directs it. This gives us a possible and many render them power- hope that the day is not distant when less. In short, the latter have taken their automatic action will enable the machine qualities from the two extreme groups ; to practice the true sailing flight without the rowers and the sailers in order to the aid of any motor whatever.
HE bumblebee is to be ren- was expected. But this is a matter of dered almost superfluous in no importance of the “fecundating manature by a machine newly chine,” as the inventor calls it, works as patented by an Indiana in- well as he claims it does. One such ma
ventor— James M. Dennis, of chine, he asserts, is equal for fertilizing Cambridge City.
purposes to a whole swarm of bumbleThis, at all events, so far as concerns bees. clover and alfalfa plants, which have de- The contrivance is two-wheele 1 pended almost wholly upon the bumble- skeleton cart, and is intended to be driven bee for their production of seed. Where by a man over a clover field. In the there are no bumblebees there is neither rear of the axle is a horizontal frame clover nor alfalfa. Which is why our extending almost the entire width of the government, not long ago, sent several vehicle. This frame is interlaced with batches of these useful insects to Aus- numerous wires in such fashion as to tralia, a bumblebeeless and cloverless divide it up into an arrangement of country.
square meshes. Up to date, it does not appear that the It will be understood, then, that the experiment has “panned out” as well as interlacing wires join each other at right
SIDE VIEW. ShowING THE "FINGERS" OF MACHINE
FOR FECUNDATION OF PLANTS.
cart wheels, they are lifted gently and
dropped suddenly. This keeps the frame VIEW FROM ABOVE OF M4HINE FOR POLLENIZING continually agitated; likewise the fuzzy
fingers, which brush the blossoms, take
up their pollen, and deposit it upon other angles. From every joining there hangs blossoms. downward a pair of spring-shaped wire In order that clover or alfalfa shall fingers wrapped with some fuzzy stuff, produce good seed, it is necessary that such as lint or fibrous down. The fuzzy the blossoms shall be cross-pollinated. fingers thus prepared are made water- In other words, the pollen of one blosproof by dipping them in a thin solution som must fertilize another. This is a of rubber. This is highly important, task satisfactorily accomplished by the because they are the business members, bumblebee; but Mr. Dennis claims that so to speak, of the machine.
his machine does it equally well, and As the latter is driven slowly over the that it can be relied upon to fertilize clover or alfalfa field, the horizontal practically all the blossoms in any patch. frame, by an arrangement of cams, is A smaller machine is also being made made to move a few inches up and down. now for similar use among strawberry Four times during each revolution of the plants.
On a Grecian Urn
O, Attic shape ! Fair attitude ! with brede
Of marble men and maidens overwrought,
Thou silent form, dost tease us out of thought
When old age shall this generation waste
Than ours, a friend to man to whom thou say'st,
WILLIAM LEWIS NIDA
HE chief purpose of a school While the problems of heating and building is to render children ventilating schoolrooms have been fairly comfortable and to protect well solved, the science of lighting has as
their health while they are yet received little consideration, though
being taught. This protection it has been brought to our attention to health should be brought about with again and again that a greater percentthe minimum of attention from the age of school children are suffering teacher who is likely to be absorbed in from eye-strain than from any other the process of instruction.
trouble. Many eye diseases, headaches In the building of the Elm Street and nervous disorders are directly atSchool at River Forest, Illinois, the tributable to the use of the eyes under board of education has adopted an en- improper conditions. tirely new method of lighting and with When we consider that the eye, whose such success that it has already been loss is more deplorable than that of any taken up by surrounding towns.
other sense organ, is subjected to con
CONTRARY TO THE PREVAILING IDEA, ONE-STORY BUILDINGS COST NO MORE PER ROOM
THAN TWO-STORY STRUCTURES.