There are three kinds, or degrees, of portability-hand; trundle, and car.

Hand portability: It is pretty difficult to design a rigid reflector of the 6" aperture usually recommended to the beginner without bringing the weight above 50 pounds; usually it will run 100. By reducing the aperture to 4", which still provides an excellent telescope, the weight can be greatly reduced, on the basis that the weight of a telescope is roughly proportional to the cube of the aperture. It is possible to lighten the parts of a 4" telescope enough to permit carrying it like a violin case or midget outboard motor without much sacrifice of rigidity.

Trundle portability: In cases where no permanent pier can be set in the earth, yet where the owner wishes a telescope of 6" or 8" aperture, large casters or small wheels can be added to the mounting of a telescope weighing up to, say, 300 pounds, and it then can be trundled outdoors, set up, used, then trundled in again. Numerous solutions of this problem have been published in this column and every maker concocts another.

Car portability: Here weight isn't the main governing factor. The mounting should knock down in about three pieces, yet be settable-uppable without recourse to an erecting crane and short of half of one night, and be knockable-downable the same. Otherwise, no great compromise on rigidity need be made and the portable can be as useful as a fixed telescope.

Figure 1 shows an 8", car portable designed and made by C. R. Wassell, of the Wassell Manufacturing Co., oil purifiers, Muskegon, Mich. It weighs 150 pounds. Pedestal of 4" seamless steel tubing, welded. At its top, under the head, are beveled filler rings that permit adjustment for latitude, so that the telescope may be used about 2 1/2 degrees north or 2 1/2 degrees south of its home town, simply by adding or subtracting some of these wedge-shaped rings.

The axes are rugged, the hollow polar axis being 2 3/8" in diameter at the point A, Figure 2, or point of greatest bending moment, and stepped down to 1 1/4" at the other end. Ball bearing.

In place of the usual central saddle for attaching the tube to the declination axis there is a full-length piece of

1" tubing. At its ends it fits into sockets in the side of cast, machined rings. In these rings the telescope tube rotates, so that stars in awkward positions may be sighted and the finder used, without neck-wringing contortions.

This, then, turns out to be anything but a makeshift type of portable; on the contrary, it is a fine piece of work requiring no small amount of machining-as would perhaps be more evident if it were not, because of its portability, associated with the chicken-foot type of pedestal often seen on less refined telescopes.

It is possible, then, to have a really refined telescope of fairly good aperture with car portability, well, anyway, provided the back-seat driver and family manager doesn't preempt the necessary space for other things. But why not design the interior of the tube to be used as a trunk, masculine gender, for sox, spare pants, and so on? Probably good enough for a mere man on a vacation trip.

IT'S a lot of fun, as any amateur telescope maker will tell you, to invent, design, and then build gadgets to save labor, even if the actual labor saving is a minus quantity. You get your pay when you can step aside and watch them function automatically, with a self-satisfied grin on your face. Who cares about time, anyway?

Top-flight position as Public Gadgeteer No. 1 undoubtedly has now been won by Kenneth Richter, 33 Clarence Ave., Bridgewater, Mass., whose star camera works while he sleeps. It is in storage just now, as Richter is away at Harvard and in summer is running a "Chromocinemataudiographic Expedition, Ltd." (possibly "limited" refers to the funds) somewhere between Hudson Bay and the N. Pole. Nevertheless we invited him to remove the bushel from off its light, so the rest of us could see its glimmer. So---

"The desire for the instrument was born of the fact that we have but two seasons in Bridgewater-the cold season and the mosquito season, and both are too uncomfortable for visual guiding of an astronomical camera. Therefore, about a year's work was spent overcoming the discomfort of attending the camera throughout the night—the exposure is made automatically.

"At about dark, I go out, lift the cover off the instrument, and pull out the plate holder slide against a stop. Next, I go in and set a clock by my bedside for the time I want the exposure to start, also for the length of time it is to run. Then I work on a mirror, take the girl friend to a movie (though building the thing kept me so broke that this is just wishful thinking) or I go to bed.

"At, say, 2 A.M., the clock turns on the power. Outside, the camera springs to life. A small motor swings the flap shutter open, and an electromagnet holds it thereafter when the small motor has shut itself off by breaking its own circuit just as the shutter strikes the magnet. The latter is energized by a radio 'A' eliminator, to avoid the vibration of the camera that would result from the use of an A.C. magnet. This is a satisfactory source of 6-v., D.C., well filtered. Meanwhile a synchronous motor drive, using one of the hen's-teeth 4-watt Warren motors, has started to apply the diurnal motion.

"Extra features include a Nichrome wire wrapped around the lens barrel, with thermostatic control to keep the entire lens about 10° C. warmer than the outside air. This is adjustable for more heat, in case of heavier dew than usual, but it effectively prevents the condensation of moisture on the glass, and there is not enough heat to distort the image to any measurable degree.

"The 500mm f.1, f/6 lens is an anastigmat that would cut a good figure in any company.

"The cross-hairs in the finder have bright or dark line illumination, of which both the color and intensity is variable; color by cellophane filters placed before the bulb (usually red), and intensity by a rheostat swiped from my radio-enthusiast brother's stock of parts.

"Well, the camera purrs along until the clock tells it to shut up. Then the power goes off, the shutter magnet is released, and the shutter closes. The spring that holds the plate holder slide is released, and the slide snaps into place. The drive motor and heater shut off, and, to cap the climax, a counterbalanced cover claps shut on the whole works.

"But suppose I am sound asleep and it rains? Two copper strips placed l/64" apart and liberally sprinkled with table salt are placed in an exposed position on the baseboard, but at the bottom of a hole so that wind will not blow the salt away. Each of the strips is a terminal in a relay hookup, so that the salt will dissolve in the first drop of rain water, complete the electrical circuit through the adjacent copper strips, and the machine will automatically and instantly close up and go to sleep. A pointer operating in conjunction with a scale on the rim of the polar axis gear also tells, within a minute, how long the camera had operated before the weather forced a shutdown.

"While almost all the gadgets are simple enough to be foolproof in operation, the drive frequently messes up the work. Other than that, one might say that it saves me probably 2 hours' work a week. The number of hours required to build the machine would, of course, swallow up this saving for several years. However, I won't even try to justify it as a net, over-all time saver. It isn't.

"But it was fun; and, after all, that seems to be the real purpose of telescoptics."

CLEAN is the word that characterizes all the telescoptical work of D. Everett Taylor, 191 Prospect St., Willimantic, Conn., some of which has been described here before, also in "A.T.M.—A.", in his chapter on "The Refractor-Metal Parts and Mounting." No exception is his newest telescope (Figure 4) a 3" with a triplet objective of his own make. Invited to describe it, he writes:

"The objective is a rectilinear 3" triplet of 50" f.1., Chance Bros. glass, beautiful stuff. The curves are very flat, the wide field is good to the edge, the diffraction rings are round and concentric, the objective is achromatic and is automatically self-centered. Reason for this type of triplet: reduction of spherical aberration. [So far as is known, Taylor is one of only three amateurs who have made triplets, others being Selby and Grand-montagne.-Ed.]

"The 100 pounds of brass shown constitutes a mounting. Base owes its main inspiration to the Springfield mounting. Designed for a permanent base, it is, however, a success on a solid tripod.

"Base of the central sleeve over the main tube is a heavy casting with stud and thumbscrew at either end. Thus the telescope can be disassembled, taken indoors and stored. Note the slot in the side of the nearer end of the rectangular declination plate; other slot is in the end of same plate. Thus, engage first one stud, then swing into other, tighten up. All set.

"The three layers of the main tube are very heavy, 1/8" wall thickness. All were machined, then lapped to a sliding fit. Draw and focusing tubes ride on the felt in the stuffing boxes."

[Explained in "A.T.M.A."-Editor.] The proportions of this mounting are impressive, and, as usual, Taylor takes a sharply focused photograph that reveals rather than half camouflages the telescope.

LET'S say you wanted some old astronomical book—for illustration, Lowell's "Mars," published 1896—but found it was out of print. You could start out searching all the second-hand bookstores of the nation. This, however, would be something of a Job! There's a short cut by which you can do it systematically for something under a dollar and send your feeler into every second-hand bookstore in the land. Have your bookseller or your librarian insert a tiny "book wanted" notice in the weekly book exchange of The Publishers' Weekly, wait a fortnight or so and if the desired book is on the shelves of the second-hand bookstores, your bookseller or librarian will begin receiving postal-cards with bids-competitive bids, which keeps the prices down. Then take up the bid you like best and chuck the rest. Your scribe has found it works well.

Suppliers and Organizations

The Society for Amateur Scientists
5600 Post Road, #114-341
East Greenwich, RI 02818
Phone: 1-877-527-0382 voice/fax

Internet: http://www.sas.org/

At Surplus Shed, you'll find optical components such as lenses, prisms, mirrors, beamsplitters, achromats, optical flats, lens and mirror blanks, and unique optical pieces. In addition, there are borescopes, boresights, microscopes, telescopes, aerial cameras, filters, electronic test equipment, and other optical and electronic stuff. All available at a fraction of the original cost.

SURPLUS SHED
407 U.S. Route 222
Blandon, PA 19510 USA
Phone/fax : 610-926-9226
Phone/fax toll free: 877-7SURPLUS (877-778-7758)
E-Mail: surplushed@aol.com
Web Site: http://www.SurplusShed.com