Economy of the Eyes

Whilst the greatest effort has been made to ensure the quality of this text, due to the historical nature of this content, in some rare cases there may be minor issues with legibility. Explanation of the Plate fronting the Title<br><br>Fig. I. Is the Spectacle front recommended for Eyes in general; the distance between the centres of the openings which held the Glasses being 2 1-2 inches, i.e. the average distance between the centres of the Eyes.<br><br>Fig. II. Is a portrait of the Pupil of the Eye when in a state of expansion. See Chapter XII. page 73, and No, X. of the Appendix.<br><br>Fig. III. The Pupil in its most contracted state. See page 73, &c.<br><br>Fig. IV. Convenient double Folding Hand Spectacles. See page 20.<br><br>Fig. V. A Preserver, or the First Sight for Long Sighted Eyes, i.e. a Convex lens of 36 inches focus cut in half to shew its form, c.the thickness of it at the middle and at the margin of it. See page 27.<br><br>Fig. VI. The 8th Sight, for Long Sighted Eyes or 12 Inches focus. Fig. VII. No.1 Concave, or the First Sight for Short Sighted Persons. See Chapter XIII. page 85.<br><br>Fig. VIII. No.12 Concave, or the 12th Sight for Short Sighted Persons.