: focus of the phantom surface m elto the 
_ Wall, this is only true as long as it is judged to be at the dis- — 
= {tice calculated by triang | 3 ji to | | 
sie ‘s a’ a as 
_the elasticity of Stevens's (a 
| 
Se 
T. W. Backhouse—Physiological Optics. | 
Brig esand Brews- 
_ ter’s), I have not had much success; it is therefore onl. | 
_ position that these observers focussed their eyes” 
_ Wall. The effect of this would be that while the 
_ cles would tell them the image was at the true di 
