Amateur telescope makers in any community will testify to the interest their telescopes have aroused locally, some of the owners deciding they have become too popular by half, since the townspeople had learned where to get a free peep at the moon at all hours. One man threatens to "leave town or else commit suicide," in order to escape this kind of popularity, but others have enjoyed the nightly visitors. J. Milo Webster of Wyoming, Pa., has kept a visitor's book at his observatory (see pictures in "A.T.M.," pages 455, 456) and says the book was entirely filled up, last summer, with 4000 visitors' names! In Rochester, N. Y.-the optical city-they had a hobby show, with stamp collectors, painters, cactus growers, micro-biologists, engine model builders, fancy quilt makers, and telescope makers among those represented. The Rochester Astronomical Society, with a membership of 100, won the silver cup as First Prize. In that city, too, the university is apparently in contact with the telescope making hobby, as the Rochester Astronomical Society has the co-operation of the university Department of Optics.

New astronomical and telescope making societies seem to spring up daily. Photographs of two of the older clubs are shown in Figure 1. In half-tone reproduction the reader can't clearly make out features, but we have been all over the original photographs with a 2" lens and, as we used to say in the army, each club group is a "fine body of men."

WHEN we first published "Amateur Telescope Making," 11 years ago, we had no idea the hobby would take such a determined hold on our readers, but today, in addition to that book, now in its fourth edition and "going strong," we now have the new book "Amateur Telescope Making-Advanced," the sequel to "A.T.M." and 150 pages larger. This most recent book harks way back to a thought we had while lying abed about 11:23 A.M. one Sunday morning in 1925, even before the thin first edition of "A.T.M." was conceived-namely, to bring together, in one place-that is, between the same two covers-reprints of some of the things we had already been chasing up in different public libraries, at considerable inconvenience. Other items in "A.T.M.A." have been written by amateurs who took up the hobby as beginners soon after "A.T.M." first appeared. Together they show how the amateur, starting at scratch and in ignorance, has performed the feat of virtually lifting himself aloft by his own bootstraps-a process of levitation which still continues, for standards improve every year.

In dividing "A.T.M.A." into two parts, one on practical "optics" making, the second on the "more practical aspects of observing," we have had in the background of our mind the possibility that, some day, if the hobby continues marching on as it has, each of these parts could be enlarged and built into a separate book. Readers' reactions to that thought are solicited. Would there be enough market for the second book (on observing) to make it economical?-say, a sale of 3000 copies-for these books must pay their way in the world.

However, avast with thoughts of making new books for the present: what we now want most, after just a year of spare time work at home, in preparing "A.T.M.A." (all this hobby. work being done on time sneaked in between regular work on the magazine) is to do a long stretch in an overstuffed chair, with time to yawn frequently. Ho, ho, hum-haven't been to the movies in years and Mae West is on tonight. By the way, please turn in proof errors, found in reading "A.T.M.A." We save these with care, against a later edition.

In case you prefer the drawing in Figure 2, to the one on page 521 of "A.T.M.A.," you may cut it out and substitute it. When invited to make the drawing for that humorous page to provide a break between Part I and Part II, R. W. Porter sent us two drawings-perhaps we selected the wrong one. Every amateur should learn this song, a parody on the Gilbert and Sullivan light opera "Pinafore," with its catchy music.

Speaking of songs reminds us of poetry. The Enid Crawford Pierce who wrote the verses about dinosaurs, on page 196, is Mrs. John M. Pierce of Springfield, Vermont. Some think the philosophy is a bit gloomy but the verses reached us one day when we felt just that way. So we accepted them. We are born, we grow up, worry about income taxes, make telescopes, make other telescopes, and die. "What's the use-only an egg yesterday and a feather duster tomorrow." But tomorrow, unless it rains again, we may feel different.

HERE is an interesting note by R. W. Porter. See Figure 3: "If a template used either as a grinding or polishing tool is moved across a spherical concave disk it will automatically produce a paraboloidal surface of revolution. The tool (template) moves parallel to itself from about A to B, the disk slowly revolving beneath it."

CONSIDERABLE interest has been shown in small items regarding the theory of polish, publishedhere from time to time, the question being whether polishing is submicroscopic scratching or some kind of molecular flow. The following is from a recent article by Dr. Wilbur B. Rayton of the Bausch and Lomb Optical Co., in The Review of Scientific Instruments, Vol. 7, No. 9.

"In the process of grinding, the particles of emery plough out channels by 'springing' out a series of small chips. Apparently the emery particle serves as a point of compression building up pressure until the glass is locally strained beyond the elastic limit, whereupon a chip flies out and immediately the process begins again at a point a little farther along. The chips are removed by a process quite similar to the process by which flakes of flint are sprung out of the surface in the fashioning of arrow heads.

"The polishing process is not so well understood. The ground surface consists of minute hills and valleys. Does the polishing process remove material from the hills until all of them are reduced to the level of the bottom of the valleys or does the material removed from the hills partially fill up the valleys?

"For a long time it was known that polished surfaces on calcite crystals used in to X ray spectrometers were much less satisfactory than natural fracture surfaces. Professor Richtmyer eventually discovered that if after a calcite surface was ground, but not polished or only lightly polished, it was etched with weak acid, its behavior became equal to a natural fracture surface and, in speculating on the cause of this effect, suggested that it might be explained by assuming that the grinding process left embedded in the surface great numbers of small crystals which, although broken away from the original crystal, were lodged in pits on the surface but with their crystal axes running in all directions. Such loose crystals would be subject to attack on all sides by the acid and would therefore be dissolved, leaving a surface which might be rough but which would be completely regular insofar as crystal axis was concerned and that it would reflect X rays as a single crystal. Apparently polishing the calcite serves to make the surface appear to be continuous, the outstanding characteristic of a polished surface, but does not remove the debris left in the pits in the process of grinding. Whether there is any reason to extend this reasoning to the grinding and polishing of glass is not immediately apparent. Glass is amorphous and calcite is a crystal but in spite of this there is the thought that a polished surface on a piece of glass may be sort of a false front that makes an actually chaotic condition present the appearance of order."

WE have been looking over an accumulation of unpublished descriptions of telescopes, with photographs, and out of about 100 only nine could be found which haven't a slender "bottleneck" ("A.T.M.," fourth edition, page 130) between the tube and declination axis bearings. It seems almost hopeless to harp on that point-folks evidently will build 'em wobbly. Here on these pages are four other descriptions we ran across, with interesting features. Figure 4 shows not only a swiveling eyepiece for a Cassegrainian, but a finder which swivels around with it, remaining always parallel to the optical axis. The user can choose a comfortable position for both eyepieces. G. L. Ardery, 2051/2 West Third St., Yankton, S. Dakota, made the telescope.

Figure 5 shows one of the inverted engine block polar axes described in "A.T.M.," fourth edition, page 142. B. L. Bradley, 235 North High St., Salem, Oregon, is the maker. He also writes: "Here is a suggestion for those who may have trouble in squaring the mechanical parts of their telescope. (I had lots for a while.) I finally ran across the idea of using my 5" scope with cross-hairs to square up the mechanical parts of the 8" telescope. I carefully marked the center point of the dec. axle, both ends. Then I lined up on the center point with my 5" portable scope, putting the center point of the axle just on the crosshair. It takes two people to do this, else you may walk the equivalent of several hundred holes of golf before the center points coincide. Continue to revolve the dec. axle around the polar axle, and adjust the set screws in the T-pipe fitting until the center points coincide on the cross-hairs. I used a similar procedure on the tube with reference to the dec. axle."

Figure 6 is a sea-going telescope. H. Leroy Benfer of the Radio Department, S.S. Santa Clara, left it with us. (Incidentally, we think no more graceful steamers sail the seven seas than the Santa Clara and others of the Grace Line's Santa class. They go through the Panama Canal and down the west coast of South America, also to California. Beautiful lines, these new vessels have and we make our bow to the naval architect who laid them down.) Mr. Benfer says he gets quite a little use of his telescope though not often on the high seas. A photo of the moon he sent shows good sharp resolution of detail. Many other photographs of the moon have been sent to us, but when reproduced in half-tone they would all look exactly alike; the half-tone would knock out any excellence they might possess. This is why they are not published.

After the sea-going telescope comes a land-going one, with pedestal permanently bolted to the rear of a car (Figure 7). C. C. Miller, president of the Amateur Telescope Makers of Kansas City, concocted this mounting. He says the tube is detachable and is taken inside except when in actual use. A trout rod and line show dimly, leaning against the mounting.

AT present several are either making 20" Pyrex mirrors or flirting with the idea. How about getting up a "Twenty-Inch Club" among these aspirants? Doubtless they could help one another to a considerable extent, a 20" being quite a job to tackle all alone. Let's hear from all of them.

HERE is a note from T. E. Morgan, of the Sacramento Shopping News, 2836 Fifth Avenue, Sacramento, Calif.: "Those amateur telescope makers who have had their mirrors silvered by just anyone should inquire about the methods to be employed before entrusting them to some workman ignorant of an optical surface. Not having slightest idea of an optical surface, much less matter of a few millionths of an inch do it about as follows: Using no 5mical5 to clean the mirror, they smear rouge-probably poor rouge at best-on a cotton pad and rub the mirror in all manner of strokes and probably in spots. If they think it needs more polishing they may even use a motor driven buffer. 'Oh well,' they think, 'it's just another mirror and we'll put a film on it with no spots, and polish it well.' The remainder of the method is to the silver with heat and more rubbing of the rouge pad. It nearly happened to me"

DURING the World War there was a dearth of practical optical workers, and persons who had even elementary knowledge of optical work were at a premium. In case this nation got into war again (and let's hope it won't) it would , turn to the thousands of amateur telescope makers for help. Not, however, that every man who can tell rouge from pitch will be made a field marshal. Just a thought.

ABOUT the slip ring idea ("A.T.M.," p. 146): Frequently amateurs invent this independently. Actually it is very old. "I don't know how old the idea is," is what Prof. H. D. Curtis, mechanically-minded astronomer and designer tells us when asked, "but I feel pretty sure that Saegmuller used it on his mountings way back before 1900. In the 'Handbuch der Astronomische Instrumentkinde' the earliest mention seems to be in mountings made by Fritsch about 1893."

IT is regrettably necessary to end on a very sad note. New York papers of January first contained the following bare item: Kildarton, Armagh, Ireland, Dec. 31 (U.P.)-Canon W. F. A. Ellison, rector astronomer of the Armagh Observatory since 1908, died today."

This is the total of our present knowledge of the matter, though we hope soon to learn more. Rev. Ellison was about 72 years of age, and a year or two ago was made a canon of the Church of Ireland. Thousands of American amateur telescope makers will add their regrets to those of Ellison's pupils elsewhere in the world at the loss of this great preceptor who has given so much enjoyment and satisfaction to all of us.

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