VISION IN THE MOUSE 



569 



Lamp of 13 c.p. 14 cm. from red glass (single thickness) ; no light through white 

 glass 



Lamp of 16 c.p. 14 cm. from red glass; lamp of 1.69 c.p. 90 cm. from white 

 glass. 



Lamp of 16 c.p. 14 cm. from red glass; Lamp of 1.69 c.p. 90 cm. from white 

 glass. (With glasses at exits, so placed as not to reflect light) 



Lamp of 16 c.p. 34 cm. from red glass; lamp of 1.69 c.p. 60 cm. from white 

 glass 



Lamp of 13 c.p. 34 cm. from red glass; lamp of 4 c.p. 80 cm. from white glass 

 (Brightnesses equal for human eye) 



