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Page:Popular Science Monthly Volume 90.djvu/44

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��Popular Science Monthly

���is automatically closed when the left pictures appear on the screen, and the left eye-aperture is closed when the right pictures are being pro- jected.

The inventor operates the shut- ters of the viewing disk electrically to accord with the alternate projec- tion on the screen of the right and left hand films.

��Eachspectator carries a view- ing disk which has two eye- apertures operating alternately

��Giving Body Relief to Motion Pictures

THINGS about us seem solid because each eye sees from a slightly different point of view. This can easily be tested by looking through a window. Close first one eye and then the other, and the window framing crosses the view at entirely differ- ent points.

What really happens is that each eye looks "around" rather more of one side of an object than the other eye; and it is the combination of the two impressions on the brain that gives us the final impression of solidity or body.

In a system of projection for motion pictures recently patented by M. F. Sulli- van, this principle is applied so as to give an effect of reality or solidity to the film projected on the screen.

By using two films which give the point of view from each eye and projecting pictures from each film strip alternately on the screen, the impression of solidity is attained, since it is only necessary to allow that eye to view the screen when its cor- responding film picture is being projected thereon.

Each spectator, however, must carry a viewing disk with two eye-apertures. This is necessary so that the right eye-aperture

��A Sheltered Feeding Table

for the Birds IRD lovers will welcome a new idea in the construction of a bird -feeding table operated on the weather-vane principle. The device is made of white pine with a copper roof and is pivotally mounted on an eight-foot pole, so that it turns with the wind. In this way it is sheltered from storms, and the birds have a dry resting place and dry food, whatever the weather. An automatic hopper for grain is provided so that there is no waste. A wire feed-rack and hooks for suet are also arranged inside of the shelter. Two arms at the sides furnish perches for the birds and also aid in the swing of the feed-table. This arrangement answers the additional purpose of a weather vane.

The little house illustrated on the right below has a sheltered feeding table under- neath it and below that is a still smaller one. The house is commodious and attractive and will furnish housing for a number of birds.


���The feeding table veers with the wind and is therefore useful as a weather vane

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