CONTRARY TO THE impression given by some editorial writers, screw drivers and soldering irons are far more common weapons among teenagers than are zip guns and switch blades. In South Chicago recently policemen, answering a frantic matron's report that hoodlums in a vacant lot were aiming a cannon at her house, found a group from the local high school adjusting a 12-inch Newtonian reflector. Another gang, caught near Washington, D. C., turned out to be radio hams bouncing microwaves off the moon. A third, investigated by state troopers north of Philadelphia, were making static tests on a liquid-fueled rocket of their own design.

Similar gangs, many unknown to the police, are at work all over the country. The gang movement in amateur science appears to be growing, perhaps as a result of rising costs and the increasing complexity of scientific experiments. A worthwhile wind tunnel or a radiocarbon dating apparatus cannot be financed b the proceeds from a youngster's odd jobs. Hence the boys are learning to pool their resources. The combined pocketbooks, enthusiasm, energy and audacity of half a dozen youngsters seem to be equal to just about any project modern science has to offer.

This includes even a cyclotron. A group of teen-agers in El Cerrito, Calif., decided to have one although they knew that even a small cyclotron may cost tens of thousands of dollars and require such finicky adjustments that nuclear physicists sometimes spend months getting the bugs out of it. The boys, lacking the mature judgment that so often prevents adults from having fun, built their cyclotron largely out of junk parts, and it worked fine! The following account of how they did the job is by Richard C. Sinnott, a member of the group who subsequently majored in engineering physics at the University of California.

"The nucleus of the idea of the El Cerrito cyclotron, like so many nuclei, was not well defined at the beginning. Lee Danner, Charles Williams, Karl Zellmann and I were all in the same physics course at El Cerrito High. Our physics teacher, Benjamin Siegel, had encouraged us in many outside projects. We worked first on a wind tunnel, then on a Tesla coil. When these projects were completed, we felt that bigger and better things should be tried. Since E1 Cerrito is close to Berkeley, we gradually developed the idea of trying a cyclotron. During a tour of the cyclotron at the University of California Radiation Laboratory we met Louis Wouters, who became our consultant and advisor.

"Many people thought that the idea of high school students building a cyclotron was ridiculous. Others, like Dr. Siegel and Dr. Wouters, encouraged our project. Looking for a sponsor, we had a talk with Frank Schallenberger, principal of E1 Cerrito High School, and he sent us with a warm recommendation to the Superintendent of Schools, Walter T. Helms. Mr. Helms set up an account for us. The cooperation of these men will always shine as an example, to me, of the attitude of true educators. They did not discourage us nor doubt our sincerity; they assisted us as best they could, both morally and financially, and the complex project of building a cyclotron was launched with great enthusiasm and great hopes by four very young fellows.

"Let us deviate now to the more scientific aspects of the cyclotron. The operation of a particle accelerator is analogous to that of a gun. When a bullet is fired, the powder accelerates the lead slug, the barrel constrains the missile and directs it in a given path. In a cyclotron the bullet is a proton, and the constraining "barrel" is the magnetic field. The propulsive force is a high-voltage, high-frequency potential which accelerates the proton. The path of this bullet, however, is not straight but circular.

"The particle starts at the center of an evacuated circular chamber. Within the chamber a flat, hollow electrode in the shape of a half circle, the 'dee,' applies the high-frequency alternating voltage that drives the proton. Professional cyclotrons usually have two dees; ours has only one. A strong magnetic field, acting perpendicularly to the plane of this flat dee, forces the particle into a circular path, which actually becomes a -spiral path as the particle flies in wider and wider circles.

"Since a proton is a positively charged particle, it is attracted by negative charge. When the rapidly alternating voltage of the dee is negative, it attracts the proton into its hollow interior. While the proton is traveling through its half-circular path, the accelerating voltage on the dee is changing its sign. As the particle leaves, it is given a kick by the now positive electrode. The relationship between the magnetic field shaping the particle's path and the frequency of the high voltage is carefully chosen so that the particle keeps getting a kick each time it enters or leaves the dee. In the half-circle of the vacuum chamber that has no dee, it travels by inertia, still under control of the magnetic field. As its velocity increases, centrifugal force causes the particle to transverse a path of ever-increasing radius. At the end of this dizzy trip the proton collides with the target-a small plate made of the substance to be bombarded. The interaction of the accelerated protons with the matter of the target is then studied by various methods to solve riddles of nuclear physics.

"The machine can be broken down into these major parts: (1) The magnet and its power supply; (2) the electrical oscillator and its power supply; (3) the vacuum system; (4) the chamber in which the acceleration takes place; (5) miscellaneous power supplies, metering and control circuits, and so on. The construction of the machine more or less followed this sequence. Our first problem, therefore, was the magnet.

"The core of the magnet weighed about 1,000 pounds. We thought it would be ideal to make the core out of Norwegian soft iron, but it turned out that none was available at the time, so mild steel was used. The biggest problem with the core was machining. The tools in the shop at El Cerrito were not large enough, and the cost of having a commercial machine shop do the work was prohibitive. After much inquiry we found that the Central Trade School in Oakland would do the work free. The School had the facilities, and since the work had educational value for their students, they agreed to do it for us if we supplied the metal.

"Magnet wire was the next problem. At the time copper wire was scarce. We managed, however, to get about 800 pounds of No. 13 magnet wire. While the core was being machined, we wound six coils in the shop at El Cerrito High and the magnet was pretty much taken care of. It had about 6,000 turns of wire and required about 35,000 ampere turns for the necessary field. The pole diameter was six inches, which made it a six-inch cyclotron. The High School donated a welding generator which would supply 90 volts at 90 amperes. For regulation we ran the magnet far into saturation. The six coils were connected in parallel (1,000 turns) and at 90 amps we had 90,000 amp turns, far more than was needed.

"The next step was the oscillator. It was to be capable of an output of about 1,600 watts of radio-frequency power. We decided to build it at my home, and during its construction I gleaned some very important experience which I hope will be noted by those of you who have not yet worked with such equipment. I was 16 years old at the time, and the construction of such an oscillator was more dangerous than I realized. The power supply would put out 2,500 volts at about one ampere. The mechanical construction and wiring went well. Then came the big moment: turning on the power. For testing we used two 500-watt light bulbs as a dummy load. With a little adjusting the lights lit brilliantly. We were overjoyed until the lights suddenly sputtered and went out. After carefully shutting things down, I started looking around in the back of the oscillator for the trouble. About two minutes later I woke up and found myself pancaked against a wall about 10 feet from where I had been working, quite stiff and sore and somewhat dizzy. Luckily I had Karl Zellmann with me, which points to Rule No. 1: Always have another person with you when you work with lethal voltages. My errors, however, were manifold. The first thing I had forgotten was to keep my spare hand in my pocket. I had made a perfect ground with my right hand while tinkering with my left. The second thing I had forgotten was to put in a bleeder resistor for the power supply. The lights had gone out because a circuit in the oscillator had opened, disconnecting the power supply. But it had left a condenser charged to about 2,000 volts waiting for me.... We put a bleeder resistor in and eventually got the oscillator working to suit us.

"We now encountered the problem of the vacuum system; believe me it was not a brief encounter. Dr. Wouters introduced us to Edward Guyon, the glass blower for the physics department at the University of California. Mr. Guyon offered to make our glassware for us for practically nothing. He constructed our diffusion pump, traps, McLeod gauge and Pirani gauge, each item normally very expensive. He gave us hints on how to find leaks and how to obtain a high vacuum. We constructed our little system, minus the chamber, and got it working after about three weeks.

"Then came the chamber. This part of the project was tied in very closely with the vacuum system. The first chamber was designed to clamp around the pole pieces. It was in two sections and looked much like a doughnut when fastened together.

"Our goal was gradually coming into view when we put the chamber into place. We started the pumps and waited for the system to pump down; naturally it leaked. We worked for about a month trying various ways to make the system tight. One of the methods suggested incorporated the use of pneumatic gaskets, so we visited the Goodrich Development Laboratory in San Francisco. George Petelin, their chemist, let us use their facilities to make some experimental gaskets. These turned out well (so well, in fact, that when another rubber company saw them, we were offered a job). Still, after all this work, the chamber leaked. We finally got the system tight enough, however, for an experimental run. One night the oscillator was warmed up, the generator started, the secondary equipment checked, the door to the cyclotron room locked, and everyone excitedly went to the control room. With everything running smoothly, we began to regulate the magnetic field slowly, watching anxiously for the deflection of the meter that would tell us we had a proton beam. At last we got a slight deflection, showing a weak but definite beam of 1.5 microamperes. We were, to say the least, tremendously happy. Then the vacuum system began to leak The chamber filament blew out and the dee started to arc to ground. The chamber just wouldn't hold a vacuum. We decided that we must completely change its design.

"The next chamber we planned was to be made of glass. Our design was again poor and we gave it up after about a month's work.

"During this time I met Harry Kennedy, the inventor of the union melt welder, who was awarded the Lincoln Medal for outstanding research in the field of welding. He has a very complete shop in which he and his able assistant, John Patterson, do research and experimental work on various ideas and problems related to industry. Mr. Kennedy expressed some interest in our little machine, and the next thing we knew he was designing and building with us a new chamber. His experience and natural 'feel' for such problems contributed to a very practical chamber design-a design which eventually was the key to successful operation of the machine.

"A detailed account of the difficulty involved in the design of this chamber may be of use to others who may some day be presented with similar difficulties in research. At first we had considered the chamber the least of our worries. As you can see, this premise turned out to be very wrong. In the following I will attempt a partial explanation of why so much trouble was had with what would appear to be a rather simple task.

"Webster's definition of research runs: 'Careful search, a close searching. Studious inquiry; usually critical and exhaustive investigation or experimentation having for its aim the revision of accepted conclusions, in the light of newly discovered facts.' Careful search on almost any subject in modern science usually requires special equipment of some sort. In large industrial and Government-supported laboratories such equipment is readily available or easily financed. In small universities a research worker has a harder problem; he must use imagination and know-how to obtain his tools. A good researcher must also be able to correlate results. Answers to a given question in his work are often subtle and apparently ambiguous. He must be sensitive to his data and adept at careful scientific analysis of all the possibilities presented.

"Mr. Kennedy, whether he realized it or not, taught us these things by example during the designing of our vacuum chamber. He would think carefully about a problem, then take a piece of chalk and draw a sketch on the floor of his shop, enlarge on the idea, draw, discard, change, redraw, until he finally arrived at an excellent answer. We would then stand around the drawing and discuss it at length until we were all convinced it was best-best not only in final result but in process. He understood how difficult it would be to machine a given shape or assemble the machined pieces, and he took into account whether the final pieces could withstand the forces that might act on them.

"Upon Mr. Kennedy's suggestion we proceeded to construct the chamber as a separate entity, that is, not mechanically dependent on the magnet. This unit type of construction would permit us to seal the chamber and locate all leaks before placing it between the poles of the magnet. The design, needless to say, worked very well. The top and bottom of the chamber were made of 1/8-inch circular steel plates very carefully machined to tolerances of 1/1000 of an inch. The wall of the chamber was made of a slice of brass tubing of 6-1/2 inches inside diameter. The bottom plate was soft-soldered to the brass, and the top plate sealed with a thin rubber gasket. Twenty-four brass screws around the periphery of the steel plates held the top on and allowed us to adjust the plates until they were parallel to better than 1/1000 of an inch. The target was introduced through a type of Wilson seal, as were the filament and hydrogen pipe, the pump-out and the die support. The filament assembly was easily removable for repair through a ground glass joint. Use of a steel top and bottom on the chamber reduced the magnetic gap to 3/4 inch, which was desirable; it raised the magnetic field a considerable amount and, by virtue of the movable nature of one plate, allowed a sort of shimming of the field.

"We now had our chamber. Very anxiously we went to work installing it. It took a month or two to make other changes and improvements. Then everything was ready and once again we turned on our cyclotron. After a few false starts, we got seven microamperes of beam.

"This small deflection of a meter had taken two years' work and the help and advice of many educated people. But the effort was well rewarded, as is any work sensibly directed with a definite goal in mind. I had gained what amounted to a million-dollar education: I had learned vacuum technique, gained a better feel for electronics, learned how to work with people and how to convince people of the usefulness of such projects. More tangibly, as a result of my part in the cyclotron I got a job immediately upon finishing college as a research physicist at the University of California Radiation Laboratory, where I could go on with the things that interested me and actually get paid for it.

"A big point in all this is that such a project inevitably requires much work, knowledge and cooperation from people other than those immediately associated with it. I feel that scientists and educators are pleased, interested and cooperative when they see someone engaged in such a project, particularly a young person. So resolve your ideas, recruit help and launch your project. Your rewards will be far greater than you can imagine-not only in increased scientific knowledge but in the experience you will gain in human relationships and understanding. Nothing is more gratifying than working with a group toward a common goal, surmounting obstacles together, sharing and criticizing each other's ideas and eventually twisting that knob and observing a tiny deflection of a meter that eloquently says, "Good going, you have done it."

AN accurate sundial must be especially designed for its exact latitude and longitude. Each accurate dial is therefore unique. If the dial is removed to another latitude, the part that casts the shadow is no longer parallel with the earth's axis and therefore casts it incorrectly. At any other longitude the hour lines give incorrect time. This explains why the mass-produced cast-metal dials often seen on sale, though attractive, are found to be inaccurate even when set up level and correctly oriented to true north and south.

The principal pleasure from an accurate sundial is derived from designing and building it, and especially from the clear comprehension of the earth's irregular motions that is best absorbed while doing both. A sundial is seldom actually used as a timekeeper today, although in the blissful absence of a radio at my isolated summer camp I do often set my watch from a sundial which is accurate within two minutes. The object in building an accurate sundial is not really to ascertain the time but to win bets from friends who challenge its accuracy because it does not agree with their inaccurate watches.

The four accurate and scientific sundials this department describes herewith were designed by builders who had taken the necessary pains to study out the earth's motions. They are all direct reading dials which tell the time without correction from graphs or tables or by mental calculation. In sundialing this is elegance.

R. Newton Mayall, co-author with Margaret Mayall of the book Sundials, How to Know and Make Them, designed the first of these dials and supervised its construction. It was given to the National Bureau of Standards by its staff, in appreciation of Lyman J. Briggs after his retirement as director. The details of its essential parts are shown in Roger Hayward's drawing on page 160.

The central, elliptical part of the dial plate is a simple dial for telling the apparent (sun) time. It has a flat-topped gnomon (shaft) which casts its straight shadow to the left in the morning and to the right in the afternoon. The gnomon is parallel with the dial plate, which in turn is parallel with the earth's axis and therefore points to the celestial pole. If the earth revolved around the sun at a uniform speed in a circular orbit, and if it were not for the obliquity of the ecliptic, a simple sundial like this would always be accurate. Unfortunately for lazy sundial builders, the earth's orbit is not a circle but an ellipse, with the sun nearer one end than the other. When the earth is nearer the sun, gravitation moves it faster, which makes the sun seem to move faster. The eccentricity of the earth's orbit and the obliquity of the ecliptic (which is due to the tilt of the earth's axis) combine to make sun time as much as 16-1/2 minutes fast in November and 14-1/2 minutes slow in February.

The difference in hour angle between the sun and a clock, which runs at a uniform rate, is the "equation of time." A plot of these differences through the year gives a curve shaped like the figure 8-the so-called "analemma" which is familiar on globes of the earth, where young people see it and embarrass older people by asking them to explain it. On the Briggs dial this analemma is mounted with a radius of curvature equal to its distance behind a small hole in a projection at the top of the dial plate. It is set off from the center far enough to the side to allow for the length of time that it takes the earth to turn from the center of the time zone to the longitude of the dial. Noon by sun time comes when the small spot of light from the sun bisects the -meridian line of the analemma, but by clock time it is noon when the spot bisects the analemma curve. Civilization runs by the constant clock and not by the inconstant sun.

To obtain correct standard time from the analemma you must be on the spot at noontime, but you can obtain it at any even hour if each hour is marked on the dial by its individual analemma. This is what the upper and lower parts of the Briggs dial face consist of. Each part has its own chisel-edged gnomon. Dividing the analemmas into halves, as shown in the drawing, adds to the dial's attractiveness and permits the insertion of analemmas for each half hour, without confusion due to overlapping. The lines incised in the bronze are filled with bright red, the references to sun time with white, and those to the calendar, with blue. It is a beautiful dial.

Without knowledge of the Briggs dial Archibald Craig of Oxford, Pa., devised a direct-reading dial of a similar type in which entire analemmas from 8 a.m. to 4 p.m. are separately inscribed. Instead of designing the dial by calculation, he let the sun lay out each analemma, visiting the dial to mark the shadow every day for an entire year.

Hermann Egger, a geographer at the International Cartographic Office in Zurich, Switzerland, says he invented the gnomic cylinder dial shown in the drawing on page 162. The Egger dial plate is tilted parallel with the earth's axis. As in the Briggs dial, the analemma is divided into two parts with two gnomons. However, instead of a flat dial plate Egger uses two cylindrical plates, one for the forenoon, one for the afternoon, set at 60-degree angles with each other. The gnomons are set at the centers of curvature as shown. In a variation not shown, two quarter cylinders are substituted for the half cylinders and the gnomon is set midway between the center of curvature and the cylinder. An advantage in using a cylindrical dial plate is that the hour angles are equal and the analemmas parallel and alike.

Egger says that a perfect sundial must meet the following requirements: It must show by a direct reading, at any hour of the day throughout the year, both the standard time and the date, and the date and hour markings must be spaced at almost equal intervals. He says that he has invented the only dials which fulfill these requirements. Any sundial in the future that casts the rays of the sun by means of four projection centers on two concave cylindric scales will be an Egger sundial, he says.

To obtain the time and the date from the sundial shown on page 164 you rotate and tilt the hour circle until a quarter-inch lens of 10-inch focal length behind a small round hole in the circle throws an image of the sun astride the line of the analemma. You then clamp it there. Russell Porter made a number of dials of this type, terminating in one built around a Pyrex flask, shown in this department in September, 1951. Herman L. Paul, a New York City machinist, saw the drawing of this dial and substituted metal circles for the flask. The outer circle is from a globe of the earth. It is placed in the earth's meridian and rotated until the axis it carries is parallel with the earth's axis. To avoid a broad shadow from the outer circle Paul removed a short segment from it and substituted a thin strip of metal. He says that the dial gives correct time within two minutes.

Neither instructions nor blueprints are available for building the dials described. Detailed instructions would require too much space and deprive a builder of his fun, while blueprints for merely copying the dials would suit but one location. "I had to study out what the whole thing meant," Paul said, adding that this was what gave him the most satisfaction. He digested the Mayall book until he clearly understood the Principles common to all sundials.

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