Planetarium Technology

Torrance Dentist

Home Telescope Design

WHO Says THE globe is not gaining far better? Suppose we have a look at it and see. Five years or so ago, when “Amateur Telescope Making” was just passing by way of its puberty, there had been two fabulous bugbears inside the telescope generating art- making pitch laps and silvering telescope mirrors. Then quite a few males of science discovered a strategy to apply coatings of reflecting metal on glass by evaporation in vacuo and, like a end result, far fewer mirrors are being silvered today than yesterday. Maybe silvering is headed toward the gate. Bugbear No. 1-silvering troubles-has thus been largely disposed of.

The Doorway Mat. Best: Partly reduce out. Backside: Ready for organization

And now Bugbear No. 2 is also on the way out. You whose dispositions have been wrecked by pitch lap creating might make your salaam to 4 modest guys in Pittsfield, Mass. and Bridgeport, Conn.- Everest, Munn, Morse, and Carlson, for these benefactors have now taken the bug out for the second bugbear. Thanks to them it is possible to now make a lap in your sleep, that may incredibly very well be as uniform and best as a waffle. The Pittsport Doorway Slat may be the answer. The image shows (bottom 50 percent) what the P. D. M. is like, and the series of pictures around the page you are reading displays just how it is actually applied. It will be a specially designed, specially put together grid of versatile rubber which you lay to the glass application, fill with melted pitch, strip off and, lo, your lap is made and devoid of any of those idiosyncrasies which, as you nicely know, will somehow or other turn up in an ordinary pitch lap no subject how a excellent deal profanity you direct at it while working on it.

Closely examine the photograph (left)!!! The mat, when prepared for use, looks as demonstrated for the backside. Its thickness is 3/16″, its size 12″ x 12″, and therefore the grid is prepared up of members of flexible rubber cast in one piece and having a cross-section like that of the typical channel inside a pitch lap-that is, l/4″ wide on the facet which casts the top associated with the channel, and about 50 percent as substantially from the aspect which lies close to the glass device and makes the bottom within the channel. The mat gives facets a single inch square and all alike. When the gate mats 1st come from the producer there’s a thin rubber net over the whole of a individual aspect, and this must be cut away prior to the mat may be utilized. At the high about the identical image that career is demonstrated partly accomplished. A sharp chisel or sharp wet knife often is the most beneficial software to us for this Of course, the manufacturer could himself do this labor but the mat would then price you considerably more than the dollar it does price, hence you get the mat plus some exercise, and no additional charge for the latter.

To use the entrance mat, according to Everest, you position the instrument, face up, with a table and tie a string loosely close to it, or snap over a rubber band or two. Then you lay the mat on top-all as revealed in Determine 1.

Fig. 1-The start

Next insert cardboard strips close to the edge, for dams (Determine two).!.! Everest says that pitch applied in such tiny amounts as an individual facet at a time (as you’re going to see later has no tendency to creep below the rubber or by means of tiny openings close to these dams. He also writes: “We make our laps over a clean white table cloth, as demonstrated in your photos.” To the other hand, if your wife hasn’t the high-quality disposition his has, we advise the addition of the bed pad.

Fig. 2-The dams

Now (Determine three) pour melted pitch into each single from the square openings, utilizing a spoon. This identical photograph shows-at least the original does-the well-known unruly Everest hair which Porter immortalized inside a sketch in a very.T.M. It seems that when Wallie was rounding a shoulder of Pike’s Peak, on his strategy to California in ’49, a huge grizzly bear suddenly reared up near him and his hair instantly reared up as well. Considering that then he never could make it lie down or do a issue with it.

Fig. 3-Pouring

Determine four reveals the squares full of pitch. Of course it will occur to virtually anyone to pour them all to in regards to the pretty same depth. Now chill the lap beneath a cold water tap and (Figures five and 6) peel off the entrance mat. It won’t stick, and when it’s to begin with put on it needs no goose-grease to maintain it from sticking.

Now soften the lap underneath the hot water tap and press it to contact with your mirror. Then trim off the tiny irregularities caused by pressing-a uncomplicated make a difference, as Wallie states, like the modest trimming you have got constantly finished on laps in order to hold the channel open during a polishing project.

Figure 7 could be the finished job-hold up the page and squint your eye along both sets of channels. Isn’t it a dandy? Here is what Dr. S. H. Sheib of Richmond, Va., who borrowed your scribe’s door mat, has to say:

Fig. 6-It does not stick

Fig. 4-Poured

Fig. 5-Peeling off

“Dear Doc: I have tried out the home mat lent me and acquire that it does every thing that’s claimed for it. These gentlemen deserve the gratitude of all telescope nuts for relieving them in the abominable and profane position of channeling pitch. Removal of a internet is quite easily effected, as you have got suggested, with a sharp 1″ chisel, but may properly be carried out equally properly, though added slowly, using a sharp wet pocket knife.

Fig. 7-Result

“In making the lap a individual have got to remember, of course, to smear the best with the software with turpentine, and to site the center of one’s application in the corner of one among the facet squares within the regular manner. This executed, its difficult to imagine how even the most inexperienced worker can fail to make a fantastic lap each time. There is no require for rush or hurry-if interrupted at any stage, the perform might probably be set aside and resumed at any later time not having risk of injury into the lap. The V-shaped ribs about the grid exhibit no disposition to cling towards the pitch, provided the whole is nicely cooled soon after the squares are filled, but component readily, leaving beautifully straight, clean, easy channels while not a trace of pitch for the bottoms.”

Fig. 8-Hardness check

From the final photograph among the series you see Wallie testing by finger nail for hardness on his pet scale, which you’re likely to come across added to web page 364 inside the new edition of a. T. M.

We asked Everest whose baby this new factor is and he says that the “only” factor he can take credit for will be the notion. He states Ralph Munn then done the mold and also the preliminary samples, but had a tiny trouble receiving fantastic front door mats, and so he accepted the offer of H. F. Morse to complete the development at Bridgeport, Conn., where they have had extra experience with such details, and Morse was assisted by G. Carlson, also of Bridgeport. Morse then “made arrangements,” Everest says, “with a manufacturer to supply door mats at a dollar each and every to any for the maniacs who desire them.”

A good deal inside the over have got to sound a decent deal like a sales talk but, if so, it cannot be helped. and no apology is presented towards cockeyed planet for it. The four who got up the entry mat aren’t producing anything from it, and their only idea was to find a rubber goods producer who would undertake to bother with it. They discovered that doorway mats might be produced and sold, non-profit, for about 75 cents plus postage. Blame your scribe for suggesting that the price therefore be set at an even dollar, postage cost-free anywhere within the confines for this planet. It’s true, this penalizes the nearby purchaser for the benefit for the distant one particular, nonetheless it saves quite quite a bit of preliminary bother about ascertaining mailing costs to all sorts of out of-the-way places and the “injustice’ virtually certainly won’t seriously affect just about anyone.

The mangled mirror

AS there still appears to get uncertainty concerning the degree of refinement needed of a excellent optical surface, three recent illustrative focograms are reproduced on this web page. The job demonstrated over was ground and polished by an newbie, because the Pyrex, perforated major mirror for a 12-1/2″ Gregorian. The mirror is approximately an f/5. The proprietor states he sent his mirror to a man who supplied to refigure mirrors and that, when he sent it, there had been no scratches on it. A fee of 25 dollars had been quoted for its correction, he says, “up to any measurable error. ” This focogram represents the mirror when he got it hack. Not only certainly is the floor deeply scratched and scored in a amazing number of p1aces, but it might be incredibly lumpy throughout the tiny areas not scratched. Study the reproduction closely. The Ronchi bands also had been zigzag, the proprietor writes, “like a snake.”

Of program 25 bucks was too small inside the first site, to charge for refiguring a 12-1/2″ mirror-far as well small. Males like Pierce or Tinsley or Lower would most likely ask quite a bit of even more, and rightly so. But a promise that can’t reasonably be kept will want to probably not be as well freely built, while in the 1st area.

The figurer, when the make a difference was submitted to him by Scientific American, following the owner had failed to get outcome provided to refigure this mirror. But within the meantime the owner had decided to do it himself, and he was able to his quite own surprise, to produce the outcome shown at the the best. We leave it to the reader to judge which often is the much better from the two.

Exact same mirror-owner’s own job opportunity

The succeed with the backside of this column might be the 8″ main for an f/5 aplanat, an was entirely built by Mary A. (Mrs. A. W.) Everest, 15 Allengate Ave., Pittsfield, Mass., with the moral and intellectual support of her husband, Wallie Everest. She created free use of his advice, but slapped his hands whenever he attempted to touch the mirror, and he is considerably prouder of it than she is. Three 1/4″ scratches and an individual 3/4″ scratch display close to the original focogram, but they are so high-quality and thin that they did not pick up around the fifty percent tone. The tiny nick in the bottom will be the shadow of the component of your check rack. On the other hand, about 80 percent within the faults about the other (at left) focogram do show-they are so gross that a fifty percent tone could not assistance picking them up. You will find no lumps and bumps in the Mary Everest mirror-the surface area is an optical surface with easy texture. (We gave such surfaces a name, a year or so ago, however it is not decorous! The higher lights blend into the shadows in a very gradual, even transition. The edge will not be turned-note the left hand diffraction ring, as per A.T.M 371. The “crest for the doughnut” (A.T.M 262) is in the proper area, seven tenths of one’s distance from center to edge. This mirror would rate as large grade workmanship in any type of society.

Mary A. Everest’s workmanship

Probably nobody should certainly set up like a professional, paid refigurer of mirrors “up to any measurable error” who can not do high grade be effective; and maybe, if do the job seriously is to become turned out over a buzz saw, at a quoted price which makes large grade labor impossible, that truth ought in fairness on the inexperienced seeker of enable being frankly stated beforehand. These comments will also serve, it happens to be hoped, to warn the inexperienced -just the ones who are least likely to sense the same exact fact-that they really should not reasonably expect a great grade refiguring task about the 12-l/2”mirror for 25 bucks, because refiguring a mirror is practically as huge a position in some cases as building a new mirror. However, a pit or two, or a light scratch or two, is simply not as crucial a matter to notice as the surface texture (“schoolmarm’s leg,” if smooth) along with the edge-these are the two most critical points. By the way, appear in vain for the left hand diffraction ring on the middle focogram-or the upper one particular, for that subject.

We’ve purposely given no names or identifications in the over, as the motive for publishing these blunt comments is just not to hurt everyone but to warn the inexperienced about the fallacy of low-priced services in optics, and perhaps to help maintain the general standard of workmanship at a fantastic level.

PROF. C. C. Wylie, astronomer at Iowa State University, Iowa City, Ia., and President of the Midwest Meteor Society, writes that he has been sending observers above the clouds in airplanes to count meteors. “If any of your novice astronomers have airplanes and may be interested, I will most likely be glad,” he adds, “to correspond with them.” Here is a possibility to die like a accurate martyr to science-not tamely in bed.

William Tyler Olcott, 62 Church St., Norwich, Conn., author of a lot of books on novice astronomy and one of the founders of the American Association of Variable Star Observers, asks us to announce that any person which has a telescope of 3″ aperture or larger can engage in the deliver the results of the Association, which has a membership of 330. This organization is mainly beginner and its meetings bring together amateurs from numerous states. Nobody should seriously feel backward about applying for membership. Another probability to be a (live) martyr.

THE new edition of the.T.M., described elsewhere, contains a chapter emphasizing rigidity in mountings, explaining the principles of finding it, and showing how to make three massive new mountings of solid concrete which Porter, the author labels “Porter’s Follies;” also 16 good new drawings by Porter. Everest’s new chapter on HCF is just not a revision but an entirely new story, describing his successful method. Pierce has a brand new chapter on clock drives. The quoted matter on pages 234-240 has been replaced by a full, illustrated treatise on close machine figuring, by Hindle, and also make a difference on pages 337-343 of the previous edition is replaced by a valuable treatise on the calculation of sidereal time, by the Mayalls of sun-dial fame. About a dozen new notes appear in the Miscellany, also several dozen minor corrections there and elsewhere, and at the end of the book your scribe adds 3 pages entitled “A Last Word to the Beginner” and winds up with his personal immodest picture. This is in answer to several requests, but of course nobody will believe this, so go ahead-all you fellers-and tell him he’s no shrinking violet and ought to be ashamed of himself!