Sunglasses

“ If now the field lens of the ocular be made of heavy flint glass and the separation of the lenses suitably adjusted, the stronger refraction of the field lens for the blue pulls up the blue focus and brings its image to substantially the dimensions of the red, so that the eye lens performs as if there were no overcorrection of the objective. ”

“ Such glasses are usually supplied with small instruments, mounted in brass caps which screw or slide on to the ends of the various eye-pieces. Neutral tint is the best, though a combination of green and red also does well. Red transmits too much heat for comfort. Should dark glasses not be supplied, it is easy to make them by smoking a piece of glass to the required depth, protecting it from rubbing by fastening over it a covering glass which rests at each end on a narrow strip of cardboard. ”

“ Often it takes a whole year, and sometimes even longer, to polish a large telescope lens. Without this magnifying agency we should have no astronomy, and fewer scientific discoveries than we now have. The glasses people wear all have to be ground and polished in much the same fashion; opera glasses, magic lanterns, and every contrivance for bringing distant objects nearer or making them larger are dependent for their power upon glass lenses."
"Even when making glass I never dreamed it could be used for so many different purposes," answered Giusippe. ”

“ Years ago, there was a little instrument of a similar kind, sold for a penny in the streets of London, which consisted of a morsel of looking-glass set at an angle, in a pill-box, and which gave the possessor the power of seeing all that was going on behind him. Persons who wear dark preservers are often in the habit of observing all that is going on behind their backs by the reflection seen in the corner of their glasses.
Such are the principal optical recreations founded on the reflecting and refracting properties of mirrors and lenses. ”

“ The other day, going down on the Sandy Hook boat, I enjoyed a most wonderful sky without that hateful barrier of misted glasses, and I am positive I distinguished delicate shades of color that I never would have been able to see, even with clear glasses. Things seem to me now to have more form, more reality than when I wore glasses. Looking into the mirror you see a solid representation on a flat surface, and the flat glass can't show you anything really solid. ”

“ The direct light of the lamp G, as well as that reflected by the mirror and passing through the lens c, is so concentrated as to project a brilliant beam of light through the painted slide, which being in the conjugate focus of the large plano-convex lens d, the pictures on the glass are refracted in a magnified form on the white cloth P Q.
The magic lantern, therefore, consists of a box to hold the lamp, a concave mirror, and a convex lens to concentrate the light on the slide, and a second convex lens to throw the image on the screen. ”

“ Both of these must be of exceptional purity, and the shape to be given to the lenses is a matter of the utmost importance. It is in the making of this pair of glasses that the skill of the optician has to be specially put forth. So valuable indeed is an object glass which fulfils all the requirements, that it is by far the most costly part of the instrument. There are no glasses in the interior of the tube until you come to the end where the observer is looking in. This is closed by an eyepiece consisting of a lens, or a pair of lenses. ”

“ Soldiers, sailors, athletes, workmen and children have great difficulty with glasses because of the activity of their lives, which not only leads to the breaking of the lenses, but often throws them out of focus, particularly in the case of eyeglasses worn for astigmatism. ”

“ To Light a Fire with the Heat of the Sun.—A small magnifying glass, or burning glass, is simply a convex lens. It is a little piece of apparatus that every boy should always carry with him just as he does his pocket knife and compass. A lens 11⁄2 inches in diameter and having a 4-inch focus may be bought for 25 or 30 cents. ”

“ But as age advances the range contracts, and an elderly person with otherwise normal eyesight requires glasses to read a book even at twelve inches from his eye. I now require much optical aid; when reading a book, spectacles of 12-inch focus are necessary; and when studying a finger print, 12-inch eye-glasses in addition, the double power enabling me to see clearly at a distance of only six inches. ”

“ I know that, as a general rule, the public cannot see beyond its nose, but when I noticed that it was merely a freak of fashion and that the young men got themselves up as carefully as Antinous, I thought perhaps they wore eye-glasses in order to better resemble the favourite of Adrian, and I laughed at those historians who pretend that glasses are a modern invention. ”

“ Watch-glasses, which perfectly retain their transparency, have resisted every attempt to break them by crushing between the fingers, or by throwing them about indiscriminately on the bare floor. Glass plates, dishes, colored lantern-glasses, and the like, have been similarly thrown about by the handful, stood upon, and otherwise maltreated, but without the slightest injury accruing to them, except, perhaps, when a solitary specimen which had been imperfectly tempered got in with the rest. ”

“ When using an ordinary magnifying-glass we see the virtual image of the object we are looking at, but in the case of a telescope or opera-glass we see the real image of the object, formed by the large lens in front, and 132reversed again by the arrangement of small lenses next to the eye. ”

“ A dull or colorless complexion can be brightened with multicolored earclips and necklaces. The colors of the precious stones will reflect and shed their glow upon the skin. Bold colors will lend their drama to the face.
On eyeglasses, all color should be shunned. Rhinestone-studded or multicolored frames call attention to themselves. The purpose of eyeglasses is purely functional; they should be left unobtrusive, not made competitors of the clip. ”

“ Nos sportsmen déclarent que ces lunettes de motoristes favorisent l'anonymat. Ces lunettes sont de véritables masques. On fait sous ce masque ce qu'on n'oserait pas faire à visage découvert. En France il est défendu de se masquer en dehors du temps de carnaval ... ”

“ The lenses are of the dioptric order, consisting of six elements built up into a strong gun-metal framework. The internal diameter naturally varies with the size and number of the wicks, and ranges from 10 inches for a 11/8 inch single wick, to 15 inches in the case of a 15/8 inch three-wick lamp. In the larger sizes a curved plate-glass pane is fitted outside the lens as a protection from the action of the weather. These storm-panes are set in copper doors, so that the glasses may be easily cleaned and polished when the lamp is being retrimmed. ”

“ The best field glasses have each objective a triple cemented lens, and the concave lenses also [Pg 151] triplets, the arrangement of parts being that shown in Fig. 110. Glasses of this sort rarely have a magnifying power above 5.
In selecting a field glass with the idea of using it on the sky try it on a bright star, real or artificial, and if the image with careful focussing does not pull down to a pretty small and uniform point take no further interest in the instrument.
Fig. 110.—Optical Parts of Field Glass.
The advantage of a binocular instrument is popularly much exaggerated. ”

“ They are intended to be worn by travellers, to guard the eyes against the wind or the dust, and consist of two glasses, sometimes green, fitted into a bandage of leather, which is passed horizontally across the face, and is tied with ribands round the back of the head. The goggles provided for Miss M. instead of glasses, were fitted up with opake pasteboard, lined with paper, and not an aperture was left through which a single ray of light could penetrate. ”

“ A woman who wears eyeglasses will be pleasantly surprised if, for more formal occasions, she tries the effects of the lorgnon or lorgnette. Whereas eyeglasses, fixed upon the face, tend to fight with the features or with other accessories, the lifted lorgnette becomes not only an adornment but a weapon. ”

“ A helmet, whilst absolutely essential, is after all but little protection from a glare that comes from the sand all around one as from a huge mirror. We soon found that, if this glare was to be borne at all, it was by using spectacles of smoked glass, and these, fitted with wire gauze side-protectors, are also essential in the blinding sand-storms that form a frequent variation of Luderitzbucht weather conditions. ”

“ You may do more irreparable damage to the object-glass of your telescope in five minutes with your fingers than you are likely to do to the rest of the instrument in a month with a screw-driver. Remember that an object-glass is a work of art, sometimes as costly as, and always much more remarkable than, the finest piece of jewellery. ”

“ When you come to look at your own instruments, though they are very ordinary ones, you will find that the object-glass o, l is made of three lenses, flat on the side nearest the tube, and each lens is composed of two kinds of glass in order to correct the unequal refraction of the rays, and prevent fringes of colour appearing at the edge of the lens. ”

“ Certainly they should not gleam with gold nor glitter with rhinestones when one is wearing earclips. The meretricious sparkle of the eyeglass rims draws attention from the earclips—which is the reverse of the proper procedure, for well designed clips can lure attention away from the glasses. ”

“ The more care is necessary in this, because if you go below [333] your required tone, there is no sharpening it again but by grinding somewhat off the brim, which will afterwards require polishing, and thus increase the trouble.
The glasses being thus tuned, you are to be provided with a case for them, and a spindle on which they are to be fixed. My case is about three feet long, eleven inches every way wide within at the biggest end, and five inches at the smallest end; for it tapers all the way, to adapt it better to the conical figure of the set of glasses. ”

“ These glasses, by showing where the air waves are all of one direction, may reveal a current flowing in one way, while they may make great masses of air flowing in some other direction appear as of some other colour, say red, for instance; or, again, in another direction, all may look green, and it will only be necessary to keep where all is pure white. ”

“ Care should be taken never to use pocket handkerchiefs or dirty rags for wiping lenses. From the frequent use of such articles, the glasses of seaman’s telescopes get dimmed and scratched in in the course of a few years. ”

“ He was so very neat and so very clean-shaved, and he always wore an eye-glass in his right eye. It seemed to grow there, for it had no string, and he never took it out except to wipe it. At first I thought he used to sleep in it, but afterwards I found that this was a mistake. He put it in his trousers pocket when he went to bed, together with his false teeth, of which he had two beautiful sets that, my own being none of the best, have often caused me to break the tenth commandment. ”

“ He got a good glass for six hundred dollars.
His new job gave him leisure for star-gazing.
Often he bid me come and have a look
Up the brass barrel, velvet black inside,
At a star quaking in the other end.
I recollect a night of broken clouds
And underfoot snow melted down to ice,
And melting further in the wind to mud.
Bradford and I had out the telescope.
We spread our two legs as we spread its three,
Pointed our thoughts the way we pointed it,
And standing at our leisure till the day broke,
Said some of the best things we ever said. [19]
That telescope was christened the Star-splitter,
30 Because it didn’t do a thing but split ”

“ It was long before they moved, and when they moved it was with great reluctance. They stood together in front of the looking-glass, and with a brush tried to make themselves look as if they had been feeling nothing all the morning, neither pain nor happiness. But it chilled them to see themselves in the glass, for instead of being vast and indivisible they were really very small and separate, the size of the glass leaving a large space for the reflection of other things. ”

“ I look in the glass sometimes at my two long, cylindrical bags (so picturesquely rugged about the knees) , my stand-up collar and billycock hat, and wonder what right I have to go about making God's world hideous. Then wild and wicked thoughts come into my heart. I don't want to be good and respectable. (I never can be sensible, I'm told; so that don't matter.) I want to put on lavender-colored tights, with red velvet breeches and a green doublet slashed with yellow; ”

“ Is it not curious, that so vast a being as the whale should see the world through so small an eye, and hear the thunder through an ear which is smaller than a hare’s? But if his eyes were broad as the lens of Herschel’s great telescope; and his ears capacious as the porches of cathedrals; would that make him any longer of sight, or sharper of hearing? Not at all.—Why then do you try to “enlarge” your mind? Subtilize it. ”

“ You can always tell an old soldier by the inside of his holsters and cartridge boxes. The young ones carry pistols and cartridges; the old ones, grub. ”

“ WHEN father bought the lamp, or a little before that, he said to mother: "Hark ye, mother—ought n't we to buy us a lamp?"
"A lamp? What sort of a lamp?"
"What! Don't you know that the storekeeper who lives in the market town has brought from St. Petersburg lamps that actually burn better than ten päreä? [1] They've already got a lamp of the sort at the parsonage."
"Oh, yes! Is n't it one of those things which shines in the middle of the room so that we can see to read in every corner, just as if it was broad daylight?"
"That's just it. ”