FREEDOM from vibration in a telescope is usually secured-or partly secured, since this is a relative term -at the expense of added weight and loss of portability. Lyle T. Johnson had built his first telescope when in high school and found it vibrated badly in the slightest breeze. Later, when an undergraduate at the University of Wisconsin and majoring in physics, he resolved to beat the vibration devil but at the same time found that he required a portable telescope. Often these two aims tend to conflict. Figures 1 to 4 show how he worked out this practical problem on an 8" reflector.

He lived in a university dormitory with a flat deck roof and could store his telescope in the attic. To use it he had each time to carry it in five knocked-down parts up a ladder through a small trap door in the roof, and assemble it on the roof, reversing the same patient processes after observation. He built the telescope mainly of wood, and its knock-down was made possible by removing five wing nuts and loosening some others.

The pier is made of two-by-fours and opens up like a jaw when the wing nuts that attach the diagonals (Figures 1, 2) are removed. Polar axis drops out.

The polar axis is a composite of steel and wood. Apparent in the photographs is its box truss made of one two-by-ten, two two-by-sixes, and a two-by-four, the first three of these being neatly tapered. Within this box truss is a 1-1/4" steel shaft with a two-roll ball bearing at either end. Later, when a clock drive is added, it will drive the shaft continuously but the wooden truss will be movable on it to permit pointing the telescope at different objects.

The declination axis is 25" of 1-1/4" shafting with a narrow 9" pulley on the tubeward end, to which the tube cradle (Figure 3) is attached. This pulley rolls on three ball-bearing rollers (Figure 4) mounted on the wooden truss of the polar axis and there is a second bearing on the opposite side of the truss. The end thrust is taken by brass plates on the truss and there is a simple wooden declination clamp.

Because two things cannot occupy the same space at the same time, the 1-1/4" declination axis had to be offset 1-1/4" from the 1-1/4" polar axis shaft. This necessitated the addition of a small auxiliary counterweight and this Johnson states, was found to vibrate when touched-a pointer for others.

The tube is all wood, made of eight pieces each 3/4" by 2-1/4", attached to three doubled, grain-crossed, and glued wooden rings. The cell is also of wood. The tube is attached to its cradle by means of four wooden turn-buttons with wing nuts to snug them up. If during observation, the eyepiece position becomes awkward, it is but a moments work to remove the tube, rotate it in the hands and re-attach it in a new position a fairly good and simple substitution for a turning ring.

The mirror will pass the diffraction test, Johnson says, and when analyzed by the Wright method ("A.TM.", p. 257) the maximum departure is less than half a millionth inch. It is mounted on a three-point support.

The telescope is now at the Washburn Observatory, University of Wisconsin, Madison, Wisconsin, where it is used by members of the Madison Astronomical Society. Johnson (Box 236, La Plata, Md.) is now a Junior Physicist at the National Bureau of Standards.

The impression created by close examination of the original photographs under a glass is that all details of this telescope are neat and shapely-there are no cobbled-up messes-yet the cost of such a mounting should be low. This telescope is not presented as spectacular or remarkable but rather as one good, inexpensive model for a solid telescope of modest size that is within the range of the average beginner or near beginner-near beginner because it perhaps is best, all things considered, deliberately to cobble-up the first telescope and use it for a time in order to let certain practical facts sink in. As Johnson says, "This 8" telescope is superior in every way to my old 6", due to the application of experience gained in the construction and use of the first one."

STILL another variation on the original theme of the conventional pitch lap is offered by C. R. West, Timpas, Colorado, who simply ladles melted pitch on the tool from a spoon and in the desired pattern of pitch and spaces. If the pitch is placed in the correct quantities at the correct places, no channeling is necessary-just some preliminary re-heating and pressing to spread it and flatten it.

First attempts at such a lap probably wouldn't look exactly artistic but practice teaches much. For a regular polishing lap West extends a number of parallel wavy lines continuously across the lap and finds it produces a smooth mirror surface free from zones. For mirror defects he pours special laps having whatever outline he wishes. It's all quick and simple.

In the kitchen the ladies add frills to cake frostings with a kind of squirt-gun loaded with sugary goo, and something of this kind might be used for making laps similar to those of West; or this may be only a half-baked idea of your scribe's. It hasn't been tried out. A danger would be from explosion if a load of chilled pitch in it were remelted incautiously. One amateur spent several helpless weeks with his hands in big bandages as a result of applying heat to the bottom of a can of pitch. As the bottom layer melted and expanded, the pitch had no place to go and the can blew up in his face. He was really pretty seriously injured. Thereafter, when re-melting pitch in a container, he started by melting an escape channel from the top down, at one side. Worth remembering, he thinks.

THIS MONTH we have a new addition to the turret telescope family, a simple refractor (Figure 5) with an auxiliary optical flat, designed by Winston C. Juengst, New York, N. Y.

As in all turret telescope designs, Juengst's idea aims at comfort and ease of observation, as a turret is sealed equally to winter's cold and summer's 'skeeters. A simpler and neater design. from both optical and mechanical standpoints, is the chief contribution.

In Juengst's design only one extra optic, in addition to the usual refractor, would be required. This is an aluminized optical flat about 1.5 times as large as the O.G. diameter. As Porter well emphasizes, such a flat would have to be a good one, say to a tenth wave or better. However, a good reflecting telescope should be made to one eighth wave to give maximum performance, so this should not stump anyone who can make a first class reflector. Furthermore, the flat will be a valuable aid in constructing the O.G., so the same effort will serve two purposes.

Other advantages to the design are fairly obvious. All parts of the heavens and horizons can be reached with ease, and with the eyepiece always in a comfortable position below the horizontal. A large part of the telescope is within the turret, rotating upon its own axis for the declination setting, hence awkward projecting parts and weights are avoided. Both axes are as stable as could be desired, hence both ease of operation and steadiness are assured, if the construction details are well attended to. The instrument is made ready for instant use merely by removing the cap from the flat housing. Auxiliary instruments, such as a camera or spectrographic equipment, may easily be supported by the turret at the focus.

Two amateurs to whom the above description was shown, previous to publication, debated about it thus:

Nip: "This turret reflector of Juengst's is really a modified Hartness telescope in principle, see 'A.T.M.', page 50 What Juengst really does is to push Hartness' diagonal out to and beyond the objective. The telescope would be simpler to make than the Hartness type but is not so stable; also, errors in the small flat would be magnified more than in the Hartness type with diagonal close to the focus."

Tuck: "Nip is partly right. However most of the turret and related systems in 'A.T.M.' page 50 do just this. The Gerrish telescope at Harvard is identical optically to Juengst's. It is an old-timer, and appears to have been a success. The use of a flat outside the objective is old stuff, not a radical new idea."

The Nip-and-Tuck debate was then referred to Juengst who commented: "The only reasons I submitted this idea were to provide a more elegant design, mechanically, free from overhanging tubes, big counterweights, and so on; also to stimulate post-war trends toward turret telescopes, especially refracting types. Too many good observing nights are lost because one's courage is not equal to the weather. The standard tolerance for a plane outside the O.G. is 0.1 wave. Anyone competent to do a good job on the rest of the telescope should be able to make a flat of that quality. But I can't see how this design resembles the Hartness turret."

Unfortunately, on March 25, after the above item was prepared, Juengst died. He had turned professional, and was doing optical ordnance work for the Navy. He was one of our earliest amateur telescope makers and came annually to the Stellafane conventions from the time he was a boy, 15 years ago. He was a graduate optometrist, University of Rochester.

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