CYRIL G. WATES, Edmonton, Alberta, Canada, before his recent lamented death, wrote the description which follows:

"In 'A.T.M.,' page 275, F. J. Sellers describes a simple drive for small telescopes, which is based upon the principle of a weight to perform the work, and a clock to control the speed. Several years ago H. Boyd Brydon, of Victoria, B.C., a member of the Royal Astronomical Society of Canada, greatly developed Sellers' drive, improved it to the point where it has become an ideal drive for the amateur of limited means and average mechanical talents, and described it in Volume 37 of the Society's Journal.

"The Brydon drive (Figure 1) involves the use of two worms engaging with a single worm gear, a principle which is believed to be completely new, despite Solomon's dictum to the contrary. In the drawing the drive has been cut down to the barest essentials omitting such features as idlers, hand control and so on, which may be devised by the builder to suit his own tastes. The drawing shows the view straight down the polar axis, to which is secured the large wheel W. A length of braided brass (or steel) picture wire is secured at P to the roller R, around which it is wrapped five times, thence passing twice around W, again five times around R, but in the reverse direction, finally passing under the pulley to which is suspended the weight.

"R is free to turn on its shaft, except for the friction of the spring-operated clutch. With the clutch out of engagement, the weight would turn the telescope from east to west. On the roller shaft is the worm A1, engaging with the worm gear G, which may be of any convenient size. Disregarding for the moment the second worm, A2 it will be seen that the weight will turn the roller R, which in turn will drive the worm A1 and the gear G. However, the second worm A2 locks the Gear G and prevents any of the parts from moving under the influence of the weight. Nevertheless, the telescope may be moved freely in right ascension by hand, since the clutch will slip and the roller turn without affecting the worms or the worm gear.

"The shaft to which A2 is secured is attached in turn to the winding key of an ordinary alarm clock. In most such clocks the key makes one turn in six hours. Therefore, if the roller R is made exactly one fourth the diameter of the wheel W, the telescope will move at the rate of one revolution in 24 hours. The clock is, of course, adjusted to keep speeded sidereal time. "Important features of the Brydon drive are the fact that the clock does no work whatever and that the smoothness of motion is independent of the accuracy or fit of the gears, since the weight automatically takes up all lost motion. In the original design, connection between the worm A2 and the clock is by means of a simple jaw clutch fitting over the key, but we venture to suggest that A2 be secured to its shaft by a lock nut. The right-hand end of the shaft may then be permanently attached to the clock by threading or, better still, by means of a simple universal joint. The clock may be wound at any time by loosening the lock nut and turning the shaft by a suitable key.

"As stated, the drawing is diagrammatic. In the complete drive the cords cross below W, pass over idlers and thence to the roller, which is only a few inches wide instead of extending right across the diameter of W."

When replying to a question put to him by this department, Brydon commented as follows on his drive: "You might suggest the desirability of fitting a pawl to prevent the wheel between the two worms from turning backward, or trying to, and thereby putting an enormous end thrust on the worm attached to the clock. This happened in one instance. I think the trouble was too great friction in the friction plates. It can happen when the telescope is turned back toward the east, and a pawl is a safety factor."

LEO J. SCANLON of Valley View Observatory, 106 Van Buren Ave., Pittsburgh 14, Pa., writes: "I've recently had occasion to make some four-bar spiders and have devised an adjustment feature for secondary mirror supports which I've never seen before. It works fine and has provision for centering the diagonal in the tube and a tilting arrangement that's simplicity itself. For the parts I went to the bathroom."

The sketch, Figure 2, is almost self-explanatory. The four fins of the diagonal support are attached to a piece of 3/4" brass pipe 2" long. Within this is a length of 1/4" thread rod (from closet tank float ball). It is held by two brass dome nuts (used to hold closet bowl down to floor) tightened against two 1" iron washers. These are not attached to the brass pipe but held there by tension and friction alone.

The dotted line indicates extreme adjustment possible. Shifting the washers laterally permits tilting the diagonal (if the shifts are opposite) or centering it in the tube. The nuts afford a longitudinal adjustment in the tube, and the diagonal may be rotated.

SILVERED MIRRORS are believed to be largely extinct-but how largely? There is an Old Guard who stick to straight razors, stiff collars, shirt tails worn inside, and silver coatings, and continue to swear by them all. In "A.T.M.," page 102, Ellison tells how silvered mirrors may be protected from tarnishing, by means of a loose pad of blotting paper. F. J. Hargreaves of England has an even better method. He cuts out a disk of 4" corkboard, dishes it to the mirror's curvature, shellacs it and allows the shellac to dry. Then he cuts out an equal circle of wash leather (chamois skin), lays it on this disk, temporarily lays a piece of clean paper over it, and through this he presses it on the shellac with a hot iron.

He finds that, unless the chamois is everywhere in firm contact with the silver, the latter will tarnish, also that this contact does no harm to the silver.

As a check test, he removed a central circle from the chamois, choosing the area that lay behind the diagonal of the telescope, and watched the gradual effect. That patch later showed up as a round "tonsure." Tarnish.

Chamois skin is hygroscopic-thirsty -not alone when on the mirror but when off during observation, and therefore must not be given a drink by being left in the open during those intervals.

EVERY YEAR Westinghouse systematically searches out native talent in science among high school seniors the nation over and awards 40 scholarships, two for $2400, eight for $400, and 30 for $100, at colleges of winners' choice. This year by written competition Westinghouse boiled down some 16,000 applicants to 40 finalists and brought the 40 to Washington, D. C. for further boiling and entertainment.

This department was agreeably surprised, yet not surprised, to find among the 40 a keen youth with whom it had exchanged letters on things telescoptical-Kenneth Widing, 611 N. Fifth St., Brainerd, Minn. When Widing reached Washington he too was agreeably surprised to find that, of the 40 telescope making finalists present, six were amateur telescope makers and a seventh, a young lady, had started telescope making when given a refractor. Of the seven TNs, three won $400 scholarships and four won $100 scholarships; but after Westinghouse puts a finger on this promising material, various colleges usually volunteer additional offers.

Some time ago with the (easy) catalytic help of this department three wartime Roof Prism Gang "alumni," learning that polio had left Widing one-armed, laid an RFT on his doorstep. English of St. Paul dug up a spherical mirror, Broadhead of Wellsville, N. Y., parabolized it, and Johns of Larchmont, N. Y., using long probes in his shop for the search, located an RFT mounting under nine strata of post-Paleolithic telescoptical accumulations such as you, too, probably have.

Telford of Florida has helped Widing with advice on a fairly good mirror of f/8 type which he has made one-handed, but the mounting proves to be more of a problem, a sketched-up affair. Who will send this lad a good mounting for that general-purpose type of telescope? For insight, try putting it in shape with one hand behind you. There must be scads of them lying unused, supplanted by newer jobs.

Asked what originally aroused his scientific bent, as revealed by Westinghouse, Widing replied: "Telescope making was my source-inspiration and I'm a TN for keeps."

TOUCHING a point hinted at above is I an appeal from Professor Charles H. Smiley of the Department of Astronomy at Brown University, Providence, R. I., president of the American Association of Variable Star Observers, who seeks recruits for this application of telescopes made by amateurs He writes:

"What becomes of all the telescopes made by amateurs? Ingalls has said this question is as difficult to answer a that better-known question, 'What becomes of all the pins?' In an effort to determine whether possibly some of the telescope makers eventually use their telescopes for regular observations, I wrote ten letters to members of the American Association of Variable Star Observers reputed to have made telescopes. The replies told me of ten members who, together, have made 33 telescopes. In addition, these persons have suggested 14 more telescope makers in the organization.

"In the following list of the ten mentioned I include only the largest telescope made by each, with apertures and focal lengths rounded off to the nearest inch.

Prof. Walter Moore University of Louisviile, Ky. 12" f/3.5

F. E. Ellis, Cambridge, Mass. 11" f/7.6 W. S. Houston, Moundsville, Ala.10" f/8.6

R. W. Hamilton, Norwalk, Conn. 10" f/8.6

S. F. Thorpe, Louisville, Ky. 10" f/5.4

Miss Martha E. Stahr, Wellesley College,

Wellesley, Mass. 8" f/6.4

E. A. Sill, Mamaroneck, N. Y. 7", f/14.

R. A. Seely, New York, N. Y. 6" f/10

S. Park, Fall River, Mass. 6" f/7

F. J. Kelly, Fall River, Mass. 6"

"The A.A.V.S.O.," Prof. Smiley continues, "is an organization having 290 members in the United States and 16 in foreign countries. They observe regularly the magnitudes of stars known to be variable in brightness, and periodically report to the Recorder, Mr. Leon Campbell, at Harvard College Observatory. In the near future, the combined members will have completed their millionth observation. Performing well a task which would otherwise fall upon professional astronomers, these amateurs are providing the basic material on which important researches on variable stars will be made in the coming decades. Persons who think they may have some talent for the observation of variable stars may obtain information concerning the A A.V.S.O. -from Mr. Campbell at Harvard College Observatory."

STELLAFANE CONVENTION of amateur astronomers, telescope makers, and of telescopes, will be held this year on Saturday and Sunday, August 3-4. The evidence is that this time more of all three categories will hit the Stellafane trail a resounding whack than ever before, and if you are not bringing a tent or otherwise sure of accommodations, reserve them before July 1. Try Hartness House or Adnabrown Hotel, both Springfield, or Windham Hotel, Bellows Falls or Fullerton Inn, Chester -all Vt.

Porter expects to come east for the meeting-has done nothing but write about it for months. (He has also been told that a D.Sc. degree is to be conferred on him but not at Stellafane, so when you see him there he'll be Doctor Porter but still the same Porter.) Bring your telescopes; everybody else does.

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