86 
Dr. Young’s Lecture 
Fig. 12. Diagonal scale drawn on a looking-glass. 
Fig. 13. The method of applying a lens with water to the 
cornea. 
Fig. 14. The appearance of a spectrum occasioned by pres- 
sure ; and the inflection of straight lines seen within the limits 
of the spectrum. 
Fig. 15. An illustration of the enlargement of the image, 
which would be the consequence of an elongation of the eye : 
the images of the candles which, in one instance, fall on 
the insertion of the nerve, falling, in the other instance, be- 
yond it. 
Plate IV. Fig. 16. The successive forms of the image of a 
large distant object, as it would be delineated by each refractive 
surface in the eye ; to show how that form at last coincides with 
the retina. E G is the distance between the foci of horizontal 
and vertical rays in my eye. 
Plate V. Fig. 17. Vertical section of my right eye, seen from 
without ; twice the natural size. 
Fig, 18. Horizontal section, seen from above. 
Fig. 19. Front view of my left eye when the pupil is con- 
tracted ; of the natural size. 
Fig. 20. The same view when the pupil is dilated. 
Fig. 21. Outline of the eye and its straight muscles when 
at rest. 
Fig. 22. Change of figure which would be the consequence 
of the action of those muscles upon the eye, and upon the 
adipose substance behind it. 
Fig. 23. Scale of the small optometer. 
Fig. 24. Appearance of four images of a line seen by my eye 
when its focus is shortest. 
