500 THE OUTGO OF ENERGY 



in the blue-green-red solution. The yellow pig- 

 ment absorbs some of the blue and green rays. 

 The remaining rays form rose color. 



Field of Vision. Fasten in a vertical position 

 a sheet of white paper about 50 cm. high and 

 60 cm. broad. (It may be pinned to the wooden 

 stand set on edge upon the electrometer box.) 

 About 20 cm. from the left margin and 30 cm. 

 from the lower margin of the paper mark a small 

 cross. Let the subject rest his chin upon a rod 

 clamped to the iron stand in such a way that 

 the right eye shall look directly at the cross. 

 Cement the squares of black, red, green, and 

 blue papers to the ends of separate straws. 

 Carry the black square from without inwards 

 along the horizontal meridian intersecting the 

 cross. Mark the point at which the black 

 object enters the field of vision. This point is 

 the temporal boundary of the visual field in the 

 horizontal meridian. Determine in the same 

 way the boundary on the nasal side. Repeat 

 for several other meridians. A line joining the 

 points obtained will bound the visual field. 



Determine the visual field for red, green, and 

 blue. Always pass the test color from without 

 inwards. The subject should be ignorant of 

 the color to be used, and should name the color 

 as soon as it enters his visual field. 



