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that they can, is about as ridiculous, as to suppose that Infirmity on Crutches, has any chance of rivalling the Champion of Pedestrians in walking 1000 Miles in 1000 Hours. which magnify too much, or as the common expression is, are too Old. not so comfortable to the Sight as Specon Nose unless considerable care is constantly taken to always hold them exactly parallel with, and at exactly the same distance from the Eyes. The Optician easily remedies arises so imperceptibly, that I — by restoring the bend of the Sides to their original form, and new pinning the Joints of them. The majority of the Opera Glasses which are sold at Trinket and Toy-shops, magnify that many so little, and are of so little use people who have good Eyes, say with truth, that they can see as well with their naked to One of* the other, it is, — Eye— have met with many who have said but, when I have shewed them a good Opera Glass, magnifying 4 times, precisely tuned to the peculiar pitch of their Visual Organ . two Opera Glasses, magnifying about twice, fixed in the opening of a Spectacle frame, which he placed before his Eyes, like as you put on Spectacles. ' And I remember, that after a considerable sweep with the 40 feet instrument, the appearance of Qirius announced itself at a great s APPENDIX. diffused rays which excite some other colour and the consequence will be, that neither colour will be singly perceptible, but that some iniermethate colour will be seen. Truths interesting Terms to All, should be told in intelligible to All. In this instance a presbyopic was changed to a myopic sight, without any known efficient circumstance to produce it. The defects of Spectacle Glasses are either from Veins Specks Scratches- Colour — — — or false Figure. The accomplished he acquires Artist, almost as soon as would be incapable of the seeds of perfection which his Art, — pursuing it, he has been industriously cultivating during * " Were there no other use of Optics, than the invention of Spectacles for the help of defective Eyes, I should think the advantage which mankind receives thereby, inferior to no other benefit whatever, not absolutely requisite to support Life. e, from 42 to 63-— is as seldom performed properly, as either of the " The Art of Growing Old with a former. from being fatigued by sitting up after their accustomed Hour, or from other causes which distressed their Nervous System. With a Pancratic Eye-tube magnifying 270 the two Stars, were just as perfectly and as distinctly defined, and at about the distance from each other, as represented in the Engraving of the Pancratic Eye-tube facing page 118, without either rings or rays, self, &c, around them. This remark is necessary, because, Coun- — made with only One Tube which have only half the variety of powers the terfeits* are Pancratic has, and consequently, magnify only Half as low or Half as high as they ought such are only put to ordinary Telescopes, for the reason we have stated, that a low power is put to an ordinary Opera-glass. You will begin to feel the absolute necessity of using Glasses, when you want to read a small print by Candle-light, for Twelve months before you require their assistance by Day-light* Cumumbra Lamp, If You obstinately strive against — See Nature, and barbarously refuse your Ejes that assistance from Art which will enable You to see with great ease, but without which, you can- — — not see without great difficulty You will act as absurdly, as if You refused to eat when hungry, or to sit down when You are tired and will soon strain and weaken your Sight. in tion, are corrected ^ v> S &§ NJ ^ s nair I: i in is P tio po — 119 PANCRATIC EYE-TUBE. As the Eyes of Persons who have very Long or a very Short without Optical assistance either a sight, are useless —they should have Double Folding Spectacles slung round their neck; (See Chapter IV. 2, which I have worn for upwards of 31 years, and it is very nearly, if not quite, as sufficient help to me now, as it was when I first emits ; — — ployed it giving me a Sight (for objects at a moderate distance,) as 1 find, by comparison, about upon a par with common Eyes :— without my Spectacles, I am quite as Sliort« GLASSES FOR 88 sighted as some of my acquaintance who use Nos