WHEN two amateur telescope makers get their heads together over a polishing barrel-a group is started. When two friends meet on a warm summer night, and their thoughts turn to the moon and stars-a group is started. In either case, it's merely a matter of securing the companionship of others of like interest- which is the point we shall now discuss. It will be our aim, in organizing this group, to help others to enjoy the many pleasurable hours we have spent tracing out the constellations upon the deep blue of the night sky, or to have them feel the peculiar satisfaction of having achieved a telescope mirror that will show them more clearly the myriad wonders of the universe of stars. We shall have a secondary pleasure in watching others succumb to the insidious addiction of which we have experienced, grinding glass with Carbo and painting the household with rouge.

"If you have made a telescope, or purchased one, you are the logical one to start the organization. If you built your own telescope, the local newspaper would be more than willing to publish a photograph of it, with a description of your harrowing experiences in grinding, polishing, regrinding and so on. The sensitivity of the knife-edge test is always amazing to the uninitiated, and is often the one thing about making a telescope that awakens an interest which is never satisfied until the witness has performed it repeatedly on a mirror of his own making.

"If you have no telescope, write for your local newspaper short articles on objects of interest in the sky at different times, concentrating attention on a particular object, describing it in the detail that is at your command. These articles should appear more or less regularly. Soon others will seek you out and declare their interest in the same subject.

"Go to your library, and see who has been reading the astronomical books. Contact them by mail, avow your interest in the same subject, and it's an easy bet that you and your opposite get together. Answer all correspondence promptly, even if it hurts.

"Don't hide your light under a bushel. If you want to have the benefit of the experience, assistance, and personality of others, you must let them know where you are. If they're at all interested, they will get in touch with you.

"Business houses are usually willing to permit a group to set up a display of your workmanship in their show windows; it is good advertising for both of you.

"When you have secured the names and addresses of a dozen persons in your locality who are interested in astronomy or telescope making, call a meeting at the home of one of them. Have someone elected by acclamation to conduct the meeting. He will be known as President, Chairman or what-not-but as yet the group will not have a name. Do not attempt at this time to name it-a name will gradually suggest itself. When you do find it necessary to identify yourselves, make the name as concise as possible-or it will take up too much room on your meeting notices. [We forgot to mention that Mr. Scanlon's organization is known as the 'Astronomical Section of the Academy of Science and Art of Pittsburgh.'-Ed.] Have a rubber stamp made with the name on it-and give it to the Secretary.

"Meet regularly, regardless of how few attend. Remember that the best organization is not necessarily a large one. Only one person out of a thousand will be interested in your subject, and that is a high percentage.

"Make the meetings informal; don't read any minutes during the first year. Report on activity of different members; talk about latest developments in astronomy.

"Get a standard astronomy textbook, and let each member take a particular chapter in turn and explain all about it, to the best of his ability-then discuss it.

"Buy, borrow, or rent lantern slide or motion picture lectures on astronomy. Large corporations often have them for free showing; lectures can be rented from observatories for a nominal charge.

"The major activities of the group will be building and using telescopes; the telescope building will progress almost unaided after someone makes a start.

"Since it is the aim of the telescope builder to supply himself with a 'scope at low cost, using the instrument upon completion is a foregone conclusion. However, undirected observation of the skies tends to become monotonous unless one has the proper guides, such as sky maps, handbooks, and so on. It should be the duty of the Secretary to post himself upon all such publications and secure them for members of the group.

"One of the first activities of the group should be to conduct a class in elementary astronomy. There will be no difficulty in securing a standard text on astronomy, and having each member study and present to one of the meetings a selected chapter from the book. A half hour of each meeting period could be thus profitably spent.

"Start a lending library among your members. Loan each other scientific books, taking a receipt for them, and receive a promise of their return within a reasonable time. Return promptly all books you borrow.

"Photograph the constellations, moon and planets with your own modest equipment. There are books available dealing with this subject, get them through your group library. Have the photographically inclined member do the developing and printing of the plates, and make lantern slides from them. Give informal lectures with these and other slides secured elsewhere to churches, clubs, and groups gratis.

"Start a club scrap book. Keep photo graphs of the activity of the various members; clippings from newspapers and journals dealing with your hobby; photographs contributed by other amateurs or groups. Co-operate with other groups in exchanging information, ideas, and materials.

"Those without equipment may be interested in studying meteors. This field is still new and open to anyone.

"Someone with the zeal to do 'real scientific work' will want to observe variable stars. This is one work that always offers the possibility of a thrilling discovery and sudden fame-the discovery of a comet or a nova is frequent enough to be encouraging.

"Arrange visits to local points of interest; visit newspaper plants, industrial concerns using science in their business; arrange at least one visit each year to some observatory where you will have unrestricted use of a telescope of considerable power, under the direction of a sympathetic astronomer.

"Take advantage of the various talents to be found in your own group: have the mathematical shark compute an orbit or explain the movements of the planets; have the draughtsman design your mountings; have the chemist lecture on the intricacy of the silvering process; have the photographer explain celestial photography; have the skilled mechanic devise better means of moving and holding your telescope. Interest your friends who are not members of the group in your hobby; they are usually willing to help you secure materials and service at less than usual cost.

"In summary: Consider yourself a committee of one to start the organization going. When you have gathered a few interested ones, co-operate with them in every way; give freely of your service.

"Don't urge anyone to join your group. If people do not have the desire to ally themselves with you without urging, they are not the ones you want; don't have a membership campaign-build up your membership slowly and firmly.

"Make your membership requirements simple; be certain that the members are interested-be certain they are good fellows!

"Work as a group, for the interest of the group. Don't promise to do anything you can't; do more than you promise.

"Don't enjoy your hobby painfully; if you don't feel like observing on a cold night, don't do it because someone expects you to do it. If you don't feel like grinding your mirror, forget it for a few nights and read a book. Follow the hobby for the fun of it-be the master of your hobby, not its slave."

ORGANIZER Scanlon also wishes us to publish the announcement that there is to be another exhibit of amateur astronomers' work, in connection with the science exhibit at the annual convention of the American Association for the Advancement of Science, to be held this year at St. Louis, December 30 to January 4. A11 amateurs wishing to submit exhibits in the form of photographs, transparencies, or material made or used by amateurs, should communicate with him (Leo J. Scanlon) at Valley View Observatory, 106 Van Buren St., Pittsburgh, Pa. The exhibit he organized last year at the same association's meeting was a big success-a compact crowd filled the booth throughout; even Professor Einstein came.

THE spider web shown in the picture on this page is a reticle used by the amateurs at the "Astrosonus Observatory," and the picture was sent by Arthur DeVany and Bernhard Nordblum, Jr., 929 Grand Ave., Davenport, Iowa. These two state that the Midwest Meteor Society, of which Prof. C. C. Wylie of the Iowa State University at Iowa City is president, worked out this method for determining the height of meteors. The four converging rods join an open ring, the "eyepiece," and the meteor's path may be accurately read as is crosses various parts of the reticle. Two reticles, separated by 30 to 60 miles, make simultaneous readings, and the rest is a matter of triangulation. The observatory shown is near the banks of "Old Man River," and houses a 6-inch Clark. Another observatory dome near by houses a 10-inch reflector made by the group (Tri- Cities Astronomical Club), which also has on the site six cameras of wide aperture, a 115-foot sun telescope, and a comet finder. Meteor shooting is a kind of astronomer's skeet game, and said to be lots of fun.

EARLIER this year Russell Porter was ill and confined to home for about five months, but relatively few knew about it at that time. Then, just when he came on deck again and went to work, word got around that he was very ill-a sort of phase lag in news arrival. To lay the ghost of the rumor, we quote what he writes: "I am on the job now, all cylinders." Everybody will be glad to hear this. While in bed he wrote a long chapter on mountings, for the fourth edition of A. T. M.

IT seems a pity that no more spectrohelioscopes have been made. The total score is one-just one-made by Prescott of Wells River, Vermont. Someone in England made one, it is true, but did not tackle the tough part, the 13 optical surfaces as the courageous, tenacious Henry B. did. Picking up the July number of the Journal of the British Astronomical Association (by the way, why don't more join this amateur society-every club should have at least one member in it, in order to get the Journal and pass it around) we find an article by F. J. Sellers, one of the mechanical group of British amateurs and the same Sellers whose chapter on a simple clock drive is in A.T.M., and read that the mean daily frequency of solar prominences during three recent months was 8.93, a lot to look at if one had s'h'scope. He describes the 50,000-mile prominence of June 22-23, "a most remarkable prominence display. The outbreak was dense and brilliant, changing very rapidly." In the same number he describes solar prominence spectroscope, with instructions for making and using it: a grating is attached to a 30~60~90 prism, and the dispersion is large.

MORE short, compact instructions for making setting circles, also for collimating different types of telescopes, are needed for the A. T. M. Supplement, as no one person seems to be able to write complete chapters on these subjects. We have some mighty fine material for this book, and more is promised. The latter ought to be sent in soon-we are working on this book every spare minute. Please don't ask us when it will appear, for we don't yet know. It will appear as soon as limitations of necessary sleep permit, and it will surely be announced, so you won't miss it. The fourth edition of A. T. M. has just gone to the printer as we write these words (Sept. 3), but when it will be ready depends upon the time it takes this one little fella to correct first, second, and third proofs, and then read the whole book in order to make a new and more complete index-a tough job in itself. So much depends upon good luck, available time, eyesight, and strength of back, that we can't yet set a date, but you won't miss this book, either-we shall of course announce it. This one-the fourth edition-is to come out first, the Supplement later. The fourth edition will not be increased in size, but there will be a number of new chapters, in place of material which is out-moded; also numerous smaller substitutions and corrections.

BENJAMIN J. Phillips, 67 Albion St., Somerville, Mass., a member of the Amateur Telescope Makers of Boston, recently sent us one hair from his head, which he had been using for a sort of Ronchi test. When tried, this proved interesting and revealing. One hair, fastened across a supporting opening or a key ring, and used with the ordinary pinhole, throws on the mirror one element of the Ronchi shadows. It will show up a zone or a turned edge about as well as an elaborate rig with fancy slits. Someone-wish we could recall who-told us a hair comb was good for the Ronchi test and we used it thereafter. No slit-merely the lamp with a cardboard around it to keep direct light out of the right eye, and the comb used as in A. T. M., page 266, Figure 3, being simply held in the two hands without complication. The jet black bars show what the mirror looks like, very clearly. The old comb works about as well as something elaborate would.

The Ronchi is a convenient side partner of the Foucault, in ordinary mirror work, but is not generally a substitute. On a short focus mirror it is a godsend for, instead of individually testing zones, as is necessary when below about f/5 because the depth of the shadows is then a poor gage of the smoothness of the curve, you simply look with the Ronchi, and if the bands are straight you have a sphere.

HERE is a problem for somebody: perhaps it will prove too tricky and sensitive to be practical. Perfect a dingbat which will permit an instructor to coach a beginner by watching the same shadows the beginner sees as he manipulates the knife-edge. In army rifle coaching, the coach lies prone near the prone rookie, at right angles to him and, by looking into a peep hole, sees the sights and target exactly as the rookie does, and can coach him vastly better than he otherwise could do. The rookie does the holding. Through this common link the two minds make full contact all the time. The problem would not be so simple on a mirror test-more delicate.

The Society for Amateur Scientists (SAS) is a nonprofit research and educational organization dedicated to helping people enrich their lives by following their passion to take part in scientific adventures of all kinds.