#6 Why has not man a Microscopic Eye? For this plain reason, Man is not a Fly. Say what the use, were finer Optics given GOD, in the nature of each being, founds Its proper bliss, and sets its proper bounds. РОРЕ. That ingenious Optician, the late Mr. JESSE RAMSDEN, informed me, that he had ofttimes more trouble to make obstinate and ignorant persons understand that the Art of Optics could not be of any service to them, than he had to find Glasses for correcting the most eccentric aberrations from good Vision and that he found the only plan of completely convincing such troublesome Customers was, after he thought that they had sufficiently amused themselves with trying a variety of Glasses, -and had tired him, to give them a pair of Spectacles glassed with plain Glass — when they would cry out with rapture — “Aye, these will do, I can see charmingly in thesewhy-why didn't You give me these at first?!!!" Nothing, short of such ocular demonstration, could satisfy them. CHAPTER III. CASE OF A PERSON WHO COULD NOT READ IN SPECTACLES. MR. R. told me that he was once strangely puzzled, by a clever Old Gentlewoman of 79 years of age, for whom he was requested to make a pair of Spectacles. She had applied in vain, to several eminent Opticians, and no Glass could be found that improved her Sight. With all that Ambition to overcome difficulties, which was the ruling passion of JESSE RAMSDEN, he waited upon the Lady, with several pairs of Convex, and of Concave Spectacles, making quite sure, that however others had failed, he should succeed, and enjoy one of those triumphs, which constituted the Zest of his Existence, but after patiently trying every one of them, She said with a Sigh!"No, not one of these will do—I can see better with my Naked Eye. Well! what an unfortunate Creature I am, at my Age, not to be able to see to read in Spectacles!!" JESSE Consoled the Good Lady as well as he could, by observing, that many at her advanced age could hardly see at all; and that although she could not see to read Here she inter rupted him with sufficient vehemence, and, to his extreme astonishment, exclaimed, "Sir, You are strangely mistaken, Sir!—I did not tell you that I could not see to Read, Sir!-I can see to Read, Sir, as well as ever I could, I only complained that I could not see to read in Spectacles!! I can see to read very well without!!! but my Acquaintance say how charmingly they can see with Glasses, and surely, it is very hard that I cannot enjoy the same Advantage." CHAPTER IV. HAND SPECTACLES. * ARE infinitely better than any Reading Glass,* however large it may be,— but are still, not so comfortable to the Sight as Spectacles on Nose-unless considerable care is constantly "The Single Convex Glasses with which some Persons read, must be very injurious, if they be sufficiently large to taken to always hold them exactly parallel with, and at exactly the same distance from the Eyes. Double Folding Hand Spectacles (see Figure IV. in Plate facing the Title) are preferable to a Single Eye-Glass, for Short-sighted persons to view pictures, &c. &c. Moreover, the use of them is not so likely to be set down to Impertinence and Affectation a censure which all persons expose themselves to, as often as they stare about them with "a Quizzing Glass." The ingenuity of the Optician is often displayed in the formation of Hand Spectacles, and a variety of highly-finished Gold and silver mountings have been contrived — but unless the Glasses are defended by a case, as in the frame portrayed in Figure No. IV. in the Print facing the Title, they will soon admit the same object to be seen with both Eyes. For as both axes will then pass through them, one on each side of the centre, the interval of the pupils will be widened, and the refracting power of the Eyes be diminished; so that here a disadvantage is to be added to the prejudice of the convexity of the Glass,-not a benefit to be placed against it, as in the case of Common Spectacles for the Long-Sighted." Dr. W. C. WELLS on Vision, 8vo. 1792. p. 130. become scratched and spoiled. The Pearl frame is the most elegant. CHAPTER V. SYMPTOMS OF THE EYES REQUIRING SPECTACLES TO READ WITH. THE natural decay of the Sight commences, in Common Eyes, very soon after " the Meridian of Life," which, according to those who train men for Athletic Exercises, and according to DR. JAMESON,* is about our 28th, accord ing to others,† about our 35th Year. "The Crystalline Humour is clear and transparent like water - till about the 25th or 30th year of our age, when it begins to become a little Yellow towards the centre, which Yellowness grows gradually deeper and deeper, and extends more and more towards the * See Dr. J. on the Changes of the Human Body, 8vo. 1811, p. 89. + See 4th Edition of "The Art of Invigorating and Prolonging Life," by the Author of this Work, 12mo. 1822, p. 46. |