It’s funny how things you think are bad sometimes turn out to be good in retrospect. Like many of us, I was fascinated by science of all kinds as a kid. As I got older, I focused a little more on it, but that came later. Living in a small town, there weren’t many current books on science and technology, so you tended to read the same ones over and over. One day my library got a copy of the relatively new book “The Amateur Scientist,” a collection of the columns of the same name (by CL Stong) in Scientific American. (Stong) was an electrical engineer with wide-ranging interests, and those columns were fantastic. The book only contained a selection of projects, but they were great. There were more projects in the magazine, of course, most of which were outside my budget and even more outside my skills at the time.
If you clicked on the links, you probably went down a very deep rabbit hole, so… welcome back. The book was published in 1960, but the projects were mostly from the 1950s. The 57 projects ranged from building a telescope — the original topic of the column before (Stong) took it over — to using a bathtub to study the aerodynamics of model airplanes.
X-rays
There were, however, two projects that fascinated me and which I – fortunately – never came anywhere close to completing. One of them was the construction of an X-ray machine. An amateur named (Harry Simmons) had described his machine and complained that in 23 years he had never met anyone who had X-rays as a hobby. Strangely enough, at the time there was no problem with the magazine publishing his home address.
A few things were needed. An Oudin coil, a type of Tesla coil in an autotransformer configuration, produced the high voltage needed. In fact, it was the Oudin coil that got the whole thing going. (Harry) used it to power a UV lamp that he used to test minerals for fluorescence. Out of curiosity, he replaced the UV lamp with an O1 radio tube. These old tubes had a magnesium coating – a getter – that absorbs stray gas that is left in the tube.
The tube glowed in (Harry’s) hand and reminded him of an old gas-filled X-ray tube. He grabbed a film and was able to image screws embedded in a block of wood.
However, O1 tubes were hard to come by even then, so (Harry), now known as a hacker, took the obvious step of having a local glassblower make custom tubes to his specifications.
Living in an area where the library was almost empty of books after 1959, it’s no surprise that I had no access to O1 tubes or glassblowers. It wasn’t clear whether he evacuated the tubes or whether the glassblower did it for him, but the tube had only 0.0001 millimeters of mercury left.
Why did this interest me as a kid? I don’t know. And why do I care now? I would build one today if I had the time. We’ve seen more than one homemade x-ray tube project, so it’s doable. But today I’m probably able to safely handle high voltage and high vacuum and protect myself from the x-rays. Probably. Then again, maybe I shouldn’t build this anyway. But at 10, I definitely would have done something bad to myself or my parents’ house, if not both.
Then it gets worse
The other project I just couldn’t stop reading about was a “homemade atom smasher” developed by (FB Lee). I don’t know what “atom smasher” means, but it was a linear particle accelerator, so I guess that’s an accurate description.
I doubt I’d have what it takes now, and certainly not then. Old refrigerator compressors were run backwards to create a rough vacuum. A homemade mercury diffusion pump did the rest. Later in life I worked with some of these things, with scanning electron microscopes and similar instruments, but I bought them, not cobbled together from lightbulbs, refrigerators and homemade blown glass!
You also needed a good way to measure low pressure, so you had to build a McLeod gauge full of mercury. The accelerator itself is a three-foot long, two-inch diameter borosilicate glass tube. At the top is a metal sphere with a peephole through which you can see a neon lamp to judge the current in the electron beam. At the bottom is a filament.
The globe above corresponds to one on a Van de Graf generator, which produces about 500,000 volts at a relatively low current. The particle accelerator is extremely linear, but of course all cool particle accelerators today form a loop.
(Andres Seltzman) built something similar, although not quite the same, a few years ago and you can see how it works in the video below:
What could go wrong? High vacuum, mercury, high voltage, an electron beam and lots of accidental X-rays. (Lee) mentions the danger of “water hammer” in the mercury tubes. Also, (Stong) was apparently nervous enough to get a second opinion from (James Bly), who worked for a company called High Voltage Engineering. He said, among other things:
…we are somewhat concerned about the dangers involved. We fully agree with his comments about the dangers of broken glass and the use of mercury. However, we strongly feel that the potential dangers from X-rays and electrons are not sufficiently discussed. Even if the experimenter restricts himself to low atomic number targets, some production of high energy X-rays will inevitably occur when electrons of 200 to 300 kilovolts of energy are used. If currents of up to 20 microamperes are reached, we are sure that the resulting danger is by no means negligible. In addition, there will be considerable quantities of scattered electrons, some of which will inevitably pass through the observation hole.
I survived
Obviously I didn’t build either of those things, because I’m still here today. I managed to build an arc furnace from a long-forgotten book. Curtain rods held carbon rods from some D-cells. The rods were in a flower pot filled with sand. An old electrical cable was connected to the curtain rods, although one conductor went through a glass of salt water to create a resistor so the fuses wouldn’t blow.
Somehow I survived without dying from the fumes, going blind, or getting burned, but there was a burn mark on the floor of my parent’s house for many years after this experiment.
If you want to build an arc furnace, we would start with a more modern concept. If you want to read a safer old book, try the one by (Edmund Berkeley), the developer of the Geniac.
