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NO MACHINE IS NEEDED FOR grinding and polishing telescope mirrors, and only a minority of amateur telescope makers use machines, since one's two hands are a good machine. Nevertheless, among advanced mirror makers who finally tire of pushing glass by hand, or who, following Yankee tradition need les..
Rs.171.99
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IDEAL hobby for elderly people is telescope making. Equally ideal for telescope making are elderly people, for these have long since discovered the necessary patience and tenacity. E. G. Richardson, 1238 Broadway, San Gabriel, California, is 79 years young and, in sending the photograph (Figure 1) o..
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IN A Newtonian telescope either a right-angle prism or a diagonal mirror of plane-parallel glass serves to turn the light focused by the concave mirror at right angles into the eyepiece. If a mirror is used, its front surface must be aluminized or only about four per cent of the light will reach the..
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INSTEAD OF a pinhole, Russell W. Porter and others have been experimenting with a slit for the knife-edge test, and it appears there is a decided gain in delicacy. Mr. Porter sends in the following description of the new test:"Here is, so far as I know, something new in knife-edge testing:"In the la..
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IN MAKING achromatic objectives for refractors, an approach from another direction than the more familiar one described below by Patrick A. Driscoll, 39 Bateau Terrace, Rochester N. Y. While this "testplate method" involves a little more work, it requires no optical flat and avoids other headaches.A..
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MANY AN AMATEUR telescope maker has reluctantly given up the intriguing idea of using the superior Pyrex disks for his telescope mirror, because they cost so much. Here, however, is a hint that came in an informal note from Russell W. Porter, who writes: "Kirth says he's read of a German who made a ..
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ABOUT 30 years ago Professor Elihu Thomson, working entirely as an amateur like the various amateurs whose telescopes have been described from month to month in this department, made a ten-inch objective lens and mounted it in a telescope which is still in operation, as shown in the illustrations. A..
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OF THE THREE ways to make optical flats, briefly outlined by Porter in "Amateur Telescope Making," page 57, the first, or three-disk method, is described at greater length by Selby in "Amateur Telescope Making-Advanced;" the second, or Ritchey, method using concave mirror and knife-edge accessories ..
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TWO MONTHS AGO in this space we described Broadhead's mirror grinding technique, last month the question of thin mirrors was discussed, and now the two are conjoined: Broadhead making a pair of thin mirrors.Recently, Dr. John Strong, author of the widely used book "Procedures in Experimental Physics..
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IN MEASURING a room we lay the measure directly on the floor, and we do the same in measuring somewhat finer work, but when it comes to measuring the separation of two star images on a plate this method is not followed by the astronomer, too rough. Instead, he mounts a microscope above the plate, ma..
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MANY WOULD-BE AMATEUR TELESCOPE makers forego the sport of mirror making because they have no place to set up the conventional mirror-grinding pedestal. This, however, need not be an obstacle; mirrors have been ground on tables, in bathrooms, in jail, and even in a morgue on a marble slab between tw..
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AS IS pointed out in "ATM" (p. 160) the telescope maker may use a machine for his glass grinding, or he may use his hands. Either method is satisfactory. Many, however, actually enjoy the fun of cooking up a machine, also of watching it work while they lean back and smoke. From the depths of the dra..
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