Page:Popular Science Monthly Volume 90.djvu/742

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726

��Popular Science Monthly

��A Gentle but Firm Restrainer for the Insane and Delirious

A RESTRAINER for the insane or delirious, which has none of the bad ef- fects of the strait- jacket or of tying and holding, is shown in the photograph. It allows the patient the free use of his arms and legs, but at the same time checks any attempt at violence and effectually pre- vents him from get- ting out of bed.

The fastenings are concealed out of his reach and he can- not work them loose.

���The fastenings are out of the patient's reach and he cannot work them loose. The night-robe conceals the restrainer

��Determining the Best Lighting Conditions for the Eye

IN spite of its wonderful adaptability, the eye can be impaired by a poor lighting system. Hence it is that the finding of the best lighting conditions is so important a problem. An apparatus which has done much towards the solving of this problem is shown in the accompanying illustrations. It consists in reality of two instruments. One furnishes a variable source of light while the other furnishes a means for view- ing and for measuring this light.

The first of these instruments is graphic- ally shown in the diagram. A light in the rear of the instrument throws its rays upon an opal glass window after having been sent by a pair of lenses through a "wedge" of blackened glass. By varying the opening in this wedge, the amount of light emitted at the window is made to vary accordingly. The second instrument is a long box-like arrangement. Through this, an observer views the window with one eye. He notes the sensation produced by this light upon his eyes, and at the same time he measures its inten- sity. This measurement is accomplished by means of a

��small "standard" electric light which is placed in the instrument. The light from this lamp is thrown on a mir- ror placed inside the in- strument and adjacent to the front slit. Thus, the light from it and from the window can be viewed at the same time. The light from the small lamp is varied by a shutter which is operated from the outside of the instrument. Be- cause of previous cali- brations, the position in which the shutter is moved will show on a scale the exact intensity of the light let through to the mirror. Hence, by adjusting this shutter until the light from it and from the opal window are the same, the exact intensity of the latter is directly obtained from the calibrations of the shutter scale. In this way the effects of different intensities of light upon the eyes of different individuals are determined.

Of equal importance to the study of good illumination is the comparison of effects of rapidly varying intensities upon the eyes. Obviously, this apparatus assists here, also. The black wedge varies the intensity and the variation is ascertained by reading the J- difference in the posi-

j 1 tions of the shutter.

���~N

��lAMP '

BLACK WEDGE'

��NOML GLASS

��Arrangement of apparatus for subjecting the* eye to varying brightnesses. At left is a diagram showing the direction of the rays from the lamp

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