ON MAY 27, 1697, William III of England granted to one "Caleb Heathcote & Others" permission to buy from its Indian owners a certain tract of "good, bad and indifferent land" situated in what is now Dutchess County in the State of New York. One portion of the tract containing "177 acres, 3 roods and 16 perches" has turned out to be amazingly productive, not of the region's traditional hay and cider, but of teen-age amateur scientists. The annual harvest now averages .125 boy per acre, give or take a rood, a yield as high as you are likely to find in any rural area of comparable size in the U. S.

The switch from farm produce to amateur scientists came in 1931, when a young educator named Edward Pulling acquired the land and established the Millbrook School for precollege boys. The property was well equipped-as a farm. Its improvements included a cottage, a barn, a smokehouse, a pigsty and assorted outbuildings-everything but a bank account. For the latter Pulling substituted what has since proved to be an equally effective resource: the enthusiasm and energy of boys. The students of the new school quickly transformed the hayloft into a gymnasium, the stallion's box stall into a science classroom and the pigsty into a place where mathematics and Latin could be taught. Today, after 23 years, the Millbrook School has a physical plant which can be compared to that of many colleges-including a battery of well-equipped laboratories featuring fine instruments also built by the students.

How do you harness boy-power and, when you do, why does the boy develop a bent for science? Writes Pulling: "We believe that, in addition to maintaining high standards of scholarship and conduct, an independent school is obligated to educate its students for intelligent and active citizenship, and this requires above all else a sense of responsibility. Instead of merely talking about the responsibilities of community service in the age of science, we confront the boys with community problems. The result is inevitable. In clearing boulders from a hillside for a much-desired ski run the boy experiences Archimedes' principles at first hand, and in carrying the job through to completion with his fellow students he gains new insight into behavior patterns that are the domain of the social sciences.

"Perhaps the most significant thing about community service at Millbrook is that it is directed by the boys themselves. Enrollment has been kept small enough so that every boy, every year, can be challenged by at least one job of major importance to the welfare of the whole school community.

"There are no 'made' jobs at Millbrook," continues Pulling. "All are real in that they contribute in one way or another to the effective functioning of the school and add meaning and interest to the life of the boys. In several cases the community jobs constitute projects which have been undertaken for the Government. For instance, a bird-banding station is operated under the auspices of the Fish and Wildlife Service; a cooperative weather station is maintained for the Weather Bureau. At the request of the National Bureau of Standards our physics department, with the aid of a group of keenly interested students, for several years operated an ionosphere propagation measurement station, the purpose of which was to collect statistics on the behavior of shortwave radio transmission.

"Some of the projects have resulted in the construction of buildings or the making of permanent equipment. For instance, our zoological committee built and now operates the zoo building and its associated outside cages. This committee is responsible for the care and feeding of all animal and bird specimens, preparing zoological exhibits, operating the experimental station in cooperation with the biology department and conducting research programs."

Nearly every mail brings to this department of SCIENTIFIC AMERICAN one or more letters from harassed science teachers asking for sources of inexpensive telescopes and other scientific apparatus. Chalk talks, explain the teachers, are no substitute for laboratory practice. "How," one teacher asks, "can you equip and maintain a high school laboratory on a budget of $1,000 a year, or less?" Pulling appears to have found one solution. Doubtless local circumstances will prevent its full adoption by some schools. But many of its features would appear to have universal application.

When we learned that Millbrook had recently built, at a cost to the school of less than $400, a full-scale astronomical observatory-including a rotating aluminum dome, a 12-inch telescope and a shock-proof floor-we decided to make a personal visit and learn the secret of Pulling's methods.

We were welcomed by Neale Howard, teacher of mathematics, physics and chemistry, whose outstanding qualification for the job appears to be a boundless enthusiasm for working with boys. When we arrived Howard had been conferring with a student group interested in local climatology-some problem having to do with the dam and weir which the group has constructed to measure the runoff of the region. Howard excused himself and we headed for the observatory, which is situated away from the lights of the school on the opposite side of an artificial lake.

Before we had come to Millbrook, Howard had given us the background of the observatory. He wrote as follows: "I think I should explain that we have no illusions about turning out scientists here. Our job is to prepare boys for college. We try to create an atmosphere in which they find it easy to accept social responsibility. In the course of this many develop a relish for science and, incidentally, nearly all of them wind up with a scientific avocation. Some, of course, go on to professional careers in science.

"We have a conviction that a boy should get his hands dirty on machinery. Many a scientifically-minded student has emerged from high school with his head crammed with the book facts of basic and applied science. He may be able to rattle off the names of the planets and the sequence of their orbits. But when he looks at the sky his expression is likely to be one of educated ignorance. He may have a smattering of astronomical knowledge, but, if so, it's usually on a par with that of the man who ducks into a planetarium for 10 minutes to get out of a rainstorm. He is totally unaware that a knowledge of astronomy can provide more enjoyment in later life than almost any other science, and that no hobbyist is more enthusiastic about his avocation or follows it with more avidity than the amateur astronomer.

"Let me admit that the curriculum of many schools is already crowded and that the addition of another course might prove to-be the last straw. But what keeps most educators from embarking on a thoroughgoing program in astronomy is their budgets. Yet it can be shown that astronomy, or any other science for that matter, does not have to be either a time-consuming course or an item of heavy expense.

"The Millbrook astronomy program started in 1946 when, with the sympathetic help of a teacher, a group of boys built a telescope. It was a tubeless wooden affair, but it set a whole program in motion. Of course it was soon followed by a more elaborate instrument-no amateur is ever satisfied with his first telescope. Although this second telescope was a good one, it was far from expensive to build. It was constructed from such items as an old lawn-mower sharpener, which provided gears for the slow motion, a junked force pump, various pipe fittings and the top of a fire extinguisher. It is still being used.

"Up to this time the work in the subject had been on a hobby basis, but the School soon recognized its value and not only provided working space for an optical shop in the basement of one of the dormitories but also allocated working time by incorporating the project into the community service program. This meant that the boys could have the equivalent of four school periods a week to use as they wished. Their first act was to convert their working space into a laboratory for grinding mirrors and lenses. Soon there were many boys working on their own telescopes. More important, they were asking for instruction in astronomy and voluntarily giving up free time to learn more about it. The whole program up to this time-it had now been going for two years-had cost less than $60, which covered the two telescopes. There were more than 20 boys taking part in it.

"The more they learned, the more they wanted to learn. Like most amateur astronomers, they wanted bigger and better instruments to work with. The outcome was a demand for a 'big' telescope. The School provided the money for a 12-1/2 inch glass disk, and the boys set to work converting it to an astronomical mirror. By the fall of 1948 they had completed the mirror and mounted it in an oak tube supported by a wooden yoke framework for an equatorial mounting. This arrangement was neither beautiful nor easy to operate, but there was nothing wrong with the optical system and for five years it provided instruction and fed the enthusiasm of many boys. Again, the only expense involved was for the mirror blank, war surplus eyepieces and finder, and the wood for the mounting. If the thing had been made of gold it would have been worth it for the stimulus it provided. One outcome was a request for a course in celestial navigation, which was provided on a hobby basis by the School; another was membership in the American Association of Variable Star Observers; still another was the beginnings of a Schmidt telescope, a project which has resulted in a nearly completed primary spherical mirror 14 inches in diameter. The most impressive outcome was the carry-over into other fields. One boy gained an insight into the principles of optics which, in the light of his subsequent career, must be characterized as profound; another studied material far beyond the scope of ordinary secondary-school chemistry because he had become fascinated with the subject through his efforts to silver a mirror. All of the boys learned a great deal about precision measurements and how to handle tools and equipment.

"The 12-1/2 inch telescope had one serious drawback: its size. Winters in New York State are not conducive to outdoor work at night, and the telescope was so big it could not be enclosed in anything smaller than a gymnasium. Since it was in an exposed location, little observational work could be done during the cold months, which was a source of unhappiness to the group. They insisted on undertaking work which extended through the year and had meaning and continuity. They wanted, for example, to set up a variable-star observing program and see whether they could interest professional astronomers in their results; to conduct a program of sunspot observations and make an effort to correlate sunspot activity with radio propagation; to experiment with celestial photography; to observe and measure the height of the aurora. In short, they weren't content to have built a telescope, which is too often the sole end of the amateur, they wanted to use it for something. But it seemed important to use it under circumstances which were at least reasonably comfortable. They decided to take their problem to the headmaster. Since a project like this was right in line with the community service program, they obtained his enthusiastic help and support and came away from the meeting resolved to build an observatory.

"The old telescope already had an excellent optical system which could be transplanted to their new enterprise. Consequently their chief need was the building itself and an adequate mounting. This was a real problem and required money. Careful planning was necessary, and so, in their mechanical drawing classes, they laid out plans and made estimates, and came up with the answer as to how much money they needed. Their next step was to make up a brochure outlining what they had done to date (complete with photographs) and what they hoped to do, and to distribute copies to everyone they thought might possibly help. The response from interested parents and friends was immediate and generous, and in an incredibly short time they had raised over $1,000. By Christmas of 1952 they were ready to start. All this was done by six boys: Michael Trimpi, John Stearns, Paul Ratner, Jack McLaughlin, Wendell Wickersham and Sumner Webber. They were the nucleus of a much larger group that did the subsequent work, and before the project was finished almost every boy in the School had a hand in the proceeding somewhere. During the remainder of the winter the boys concentrated on making wooden patterns for the aluminum castings in the mounting, fabricating the sheet steel base, setting up the gear system and finally assembling the whole structure. In this work they had a windfall. A local manufacturer, Gordon Anderson, became interested in their project and turned over the facilities of his machine shop to them, along with generous portions of his own time and energy. With his help they finished the mounting by spring. Then, hardly pausing for breath, they turned to the observatory itself.

"Nine weeks later they stepped back and looked at what they had accomplished. The completed structure was 17-1/2 feet in diameter, built of waterproofed cinder block and surmounted by a dome which had started life as a silo top. The dome revolved on a track set on top of the cinder block and had a four-foot slit giving access to the heavens by means of a novel and original arrangement of casement shutters. Inside, the floor was built up 2-1/2 feet over an eight-inch concrete slab, and set in the center of the slab was a massive pier which supported the telescope mounting. The latter was a far cry from the cumbersome wooden mounting the boys had wrestled with earlier. Made of steel and aluminum, it featured an open tube constructed of tubing threaded through cast aluminum rings. It had slow motion devices, slip-ring, setting circles, and needed only a motor to be complete. The astronomy committee was pretty well satisfied with what it had accomplished when they went home for the summer.

"After the boys returned in the fall they occupied themselves with odds and ends-clean-up work and laying out a program from which they could get the most use of their equipment. This was perhaps the most interesting phase of the whole project, because to the boys the construction of the observatory represented the beginning, not the end."

When we examined the structure it was clear that it was indeed a worthy beginning. The observatory met professional standards in every respect. The astronomy committee was on hand to show off its new plant, and three members-Alan Hubbard, Julian Strauss and Michael Madden-demonstrated the operation of the dome and the instrument, although, unfortunately, a heavy overcast prevented observation. Other members of the committee reviewed the current program with us and explained the significance of the data sheets and the photographic negatives made during the previous night. As the boys discussed their work it soon became plain why they had not been content merely to build a telescope. In the group discussion idea seemed to beget idea. It was easy to understand why the lone amateur often makes a telescope but does not use it. Without the challenges that arise from group discussion it is easy to overlook the thrills to be found at the eyepiece.

The members of the committee explained that they worked in two- and three-man teams. The teams are assigned as required to carry out a sequential program ranging from lunar and planetary observation through double stars, clusters and nebulae to the long established meteor and auroral work. In addition, the boys open the observatory to the student body twice each week.

The committee is now investigating the possibility of developing a program that would result in contributions of interest to astronomy itself. Plans are being laid for projects involving variable stars, sunspots, celestial transits, occultations, eclipses and celestial photography. Participation in the activity is open to anyone willing to acquire a knowledge of the constellations and other preliminary information essential to observation.

"In the course of developing the current program the boys considered many projects," writes Howard, "but recognizing both their own limitations and those of their equipment they wisely decided R to stick to these phases of astronomy in which they were most likely to be successful.

"The astronomy program has now been in effect for eight years. During that time over 100 boys have taken part in it. The total cost, including money the boys have raised themselves, has been less than $1,600. It is true that the boys have spent considerable time on this project, but most of it has been their own. Actual class time has been the equivalent of four 35-minute periods a week

"Here, then, is a way to introduce instrumental astronomy to a school curriculum. It is not presented as a universal solution to the problem, but simply as one means of attacking it. Its chief merits are that it is an inexpensive approach and that the program grows R naturally because student interest is self-generating."

A BINOCULAR is two parallel telescopes permitting the simultaneous use of both eyes. Exhaustive experiments by the National Research Council have shown this arrangement results in a 4.5 per cent improvement over a single telescope in the performance of visual tasks. For this small advantage the user pays not only for the second telescope but also for the mechanism that must keep the telescopes parallel within only two or three minutes of arc. If eyestrain is to be avoided, this alignment must hold for all openings of the central hinge. It is not always realized how difficult this apparently simple mechanical problem is. The mechanism often loses its precision, and it is the mechanism, rather than the optics, which is the source of much of the difficulty with a binocular.

G. Dallas Hanna of the California Academy of Sciences, a paleontologist-zoologist whose hobby is the fine mechanisms of scientific instruments and who in wartime headed a group of 50 men and women who completely overhauled 6,000 U. S. Navy binoculars, says that not all professional binocular repairmen do a complete job of adjustment. Some slight it by adjusting, or collimating, for only a single opening of the hinge. Moreover, says Hanna, "not even the manufacturers consistently take the trouble to put their binoculars in perfect collimation. If I had a dollar for every 'new' pair I have had to collimate, I could retire. We must remember that we are dealing with movements of mechanical and optical parts measurable by thousandths of an inch, and such displacements produce unfortunate results when magnified by the optical levers involved. The binoculars are not built- perhaps could not be built-for the rough treatment they receive from many users. It is impossible to keep the telescopes parallel. It is the general belief of shop repairmen that if the designers of binoculars would tear down a few of their instruments after they have been out in service they might alter greatly the details of their construction. Nevertheless people like the instruments with all their faults and there are millions of them in use. Because many of these faults are practically unavoidable, it can be said that a good binocular has not been made, and it is doubtful whether one ever will be." Hanna gives as his personal preference for escaping all the faults an instrument that is not a binocular at all. It is a monocular; specifically half of a 6X30 binocular.

In his chapter on the overhaul and adjustment of binoculars in Amateur Telescope Making: Book Three, Hanna provides for three levels of dealing with binoculars. The first is six quick, simple tests for evaluating a binocular in a store prior to purchase. The second goes to the other extreme: the construction of a binocular-collimating instrument by which a binocular may be adjusted so precisely that, as he says, it "may be used continuously for hours without the slightest strain, and the observer soon forgets that he is looking through an optical instrument at all." Though it is almost impossible to attain the highest degree of precision without a collimator of this quality, few will care to make one for a single job of collimating, so Hanna describes a third procedure that will give a passable result without it. To these approaches Felix A. Luck added in this department for October, 1951, a method for making and using a collimator that could be built mainly of wood in a few hours and which would give a reasonably close approximation using the sun. Vern E. Hamilton of Inglewood, Calif., now contributes another method which uses the sun and a homemade apparatus that can be built in less than an hour. Hanna says it should result in better adjustment than some of the binocular repair shops turn out. Hamilton writes:

"Here is a method requiring no precision equipment and by its very nature giving collimation at all interocular settings, not at one average setting alone. I believe it could be called a 'primitive' method since nothing need be square and no measurements are made, the disks being drawn with a primitive instrument, the compass.

"At right angles to one end of a two-by-four about eight feet long, fasten a white cardboard focusing screen about two feet square. At the other end fasten an adjustable mount for the binocular so that it will be approximately in line with the center of the focusing screen. This mount should be designed so that half of the binocular may be clamped securely while the other half is being swept through the interocular adjustment.

"Focus the eyepieces for distance and place the binocular in the mount. Point the whole arrangement toward the sun, so that two enlarged images of the sun fall on the focusing screen. Cut from cardboard two separate disks about two inches larger in diameter than these solar images. When arranged in the manner about to be described the disks will cast a shadow with a fuzzy edge, or penumbra, and an area of total shadow, or umbra, which will be slightly larger than the solar images. In the center of the disks cut a hole just the right diameter to slip snugly over the binocular eyepiece. Cut a rough quadrant out of each disk so that it will clear the other eyepiece, and press the disks onto the eyepieces.

"When the arrangement is again pointed at the sun, the disks will cast a shadow large enough to hide completely the shadow of the binocular itself. Cover the right objective, clamp the right side of the binocular firmly, and put the left side at one extreme of the interocular setting. Adjust the mount by moving the entire binocular so that the solar image on the focusing screen is centered on the left disk shadow.

"Now, while sweeping the left side of the binocular through the entire interocular adjustment to the other extreme, note any shifting of the solar image in relation to the disk shadow. If the solar image remains centered with the disk shadow, the left optical axis is parallel (collimated) with the interocular adjustment axis. If, on the other hand, there is a relative movement between the solar image and disk shadow, rotate the mount (moving the entire binocular) by cut-and-try until a position is found where the solar image and disk shadow will remain fixed in relation to each other (but not centered) while being swept back and forth through the interocular adjustment. When this condition is obtained, adjust the optics of the telescope so as to bring the solar image on center with the disk shadow. If all has gone well, the solar image will now remain centered on the disk shadow while the left side is swept through the interocular adjustment. If not, repeat the entire sequence as a refining process with each side until the binocular is collimated. As a double check remove both objective covers and see whether both solar images can be centered on their corresponding disk shadows at each extreme of the interocular setting. If there is any accumulated error, repeat the steps with the individual telescopes until no error is detectable, or at least until no error is detectable at your own interocular setting. Thus, instead of disregarding the interocular adjustment axis, it is used as the common reference line for collimating the two binocular telescopes.

"This method is based upon the fact that in a properly collimated binocular any two corresponding pencils of light from the eyepiece are parallel to each other, and the central pair must be parallel to the interocular adjustment axis if the telescopes are to be parallel to each other at all interocular settings. The parallel rays of the sun are used to construct base lines and project the exit pencils simultaneously. The sun, eyepiece disks and disk shadows form the base lines, and the solar images represent the exit pupils. When the binocular is oriented in space so that the solar images can be made to remain fixed (but not necessarily centered) in relation to the disk shadows while being swept through the interocular adjustment, then the adjustment axis is parallel to the base lines. After this condition is obtained, the optics are adjusted to bring the solar images on center with the disk shadows. The solar images (representing the exit pencils) will now satisfy the full requirement for collimation by remaining centered as well as fixed in relation to the disk shadows (base lines) while being swept through all interocular settings.

"If it is desired to collimate the binocular for one interocular setting, the method reduces to an extremely simple one. The only requirements are the cardboard masks for the eyepieces and a focusing screen propped up on the ground approximately at right angles to the rays of the sun. The binocular is set at the desired interocular setting and pointed at the sun so that one of the solar images is centered on its disk shadow. The optics of the other telescope are then adjusted to bring its solar image on center with its disk shadow, and the binocular is collimated for a single setting. Of course, if one does not wish to tackle the job of collimation, the foregoing simplified method may be used to check quickly the collimation of a doubtful binocular without any disassembly whatever.

"The amount of error may be estimated by aligning one solar image with the corresponding disk shadow and estimating the displacement of the other solar image and disk shadow. This displacement, divided by the distance from the binocular to the focusing screen, is the tangent of the apparent error angle. The apparent error angle divided by the power is the actual error angle.

"The formulas in Donald H. Jacobs' Fundamentals of Optical Engineering give a tolerance for non-parallelism in 7X binoculars of only 3.75 minutes of arc for convergence and 1.3 minutes for divergence horizontally and/or vertically. On a focusing screen eight feet away 1.S minutes of arc amounts to one fifth of an inch off-center permissible between solar image and disk shadow. This amount can be detected by the method, and it is best not to leave any detectable vertical or horizontal divergence in the binocular at all. As indicated, some convergence can be left, provided that it -does not turn into divergence as the binocular is swept through the interocular adjustment."

Practical objections have been raised to the adverse effects caused by the earth's rotation when using the sun with this method. Hamilton says: "This gives some trouble, but the error need not be left in, since the rigorous check is made by setting the binocular at one extreme interocular setting with the telescopes uncovered. The solar images are set to 'lead' the shadows and the solar images are watched until the earth's rotation -brings them onto the shadows, when they are compared for on-center. This is repeated at the opposite extreme interocular setting. Any small error which may have accumulated from the previous steps can thus be detected and the steps repeated with the individual telescopes to bring the error within the acceptable limits. ~

"The fuzzy shadow of the cardboard disk is a very real problem, and its only solution lies in the fact that checking with the solar image utilizes the 'sense of symmetry' enhanced by the apparent -doubling of the eccentricity. I usually work inside the fuzzy penumbra by making the solar image a little smaller even than the umbra, and if the image is off center, say one fifth of an inch, the dark ring around the outside of the solar image will be two fifths of an inch narrower on one side than the other.

"Another small source of trouble is that the solar image is not quite sharp either. Of course the eyepiece could be focused so that the solar image would be sharp, but the eyepiece would not then be in the position of average use, and since the method is sensitive enough to pick up eccentricity in the eyepiece lenses and threads, a faulty collimation would result. Incidentally, a good test when buying a binocular is to step outside in the sun, rest the binocular on a firm support and turn the eyepiece while watching the solar image on the ground. Of course the image will come in and out of focus, but any eccentricity will be readily apparent."

Bibliography

AMATEUR TELESCOPE MAKING Edited by Albert G. Ingalls. Scientific American, Inc., 1952.

AMATEUR TELESCOPE MAKING-ADVANCED. Edited by Albert G. Ingalls. Scientific American, Inc., 1952.

AMATEUR TELESCOPE MAKING-BOOK THREE. Edited by Albert G. Ingalls. Scientific American, Inc., 1953.

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