Context and sources: Work at the Explosives Research Laboratory

The Explosives Experiment Station is located on Government-owned property near Bruceton, Pa. … [L]and was leased from the Pittsburgh Coal Co. contiguous to and west of the bureau’s experimental coal mine at Bruceton, Pa, for use as a firing ground. Beginning in June, 1917, four hollow-tile, stuccoed instrument shelters, a bombproof, and several magazines were erected on this tract, and the various appliances for testing the explosives were installed. The new station at Bruceton was called the “Explosives Experiment Station.” By January 1, 1918, the station was ready for operation, and the physical tests of explosives to determine their permissibility have been conducted there ever since. The station has also been used for conducting original investigations into the characteristics and behaviors of various explosives and studying problems involving the use of explosives in mining. Since the equipment was originally installed there has been a continually growing increase in equipment and buildings…

I decided I didn’t want to stay at Westinghouse, so I was packing up there after two years as a Westinghouse fellow. And a laboratory had opened outside of Pittsburgh. Being in Pittsburgh I heard about this laboratory. I don’t remember how. It was in Bruceton, which was a division of the Bureau of Mines. They had an experimental coal mine there where they tested mine explosives. The NDRC had just been set up and they had a group of top notch people out there working on explosives. … Kistizkowsky was the head of it; MacDougall, who was a physical chemist from Minnesota, was also out there, sort of Kistizkowsky’s deputy. … I was at Bruceton for about a year and a half, working mostly on propellants, and not high explosives, though the work impinged on it. There were wonderful and very able people there.

Having finished the mine detector contract in the fall of 1942, I was looking for another war-connected problem. An organization called the Office of Scientific Research and Development (OSRD) had been established. … Dr. [Frederick] Seitz [a fellow Carnegie Institute faculty]asked me if I would be interested in one involving high explosives. My immediate reaction was strongly negative. Dr. Seitz was not surprised but said he had witnessed a demonstration of a remarkable effect he had found very interesting. “Would you be interested in going with me to the Bureau of Mines in Bruceton, Pennsylvania, to see a demonstration?” he asked. I agreed to go. The demonstration was carried out by Drs. George Kistiakowsky and Duncan MacDougall, chemists from Harvard.

The inadequacy of experimental data on detonation rates was very evident from the start of NDRC [later OSRD] work on explosives, and consequently research on this subject [under the direction of Dr. D. P. MacDougall] was one of the first projects for ERL. A high-speed rotating-drum photographic camera [by MacDougall and Messerly] was put in operation at ERL in the summer of 1941. Extensive optical studies of the process of detonation were carried out with this camera. These studies extended into 1945 and brought to light many hitherto unknown or barely explored phenomena. First in order was a systematic investigation of detonation rates of standard explosives at various bulk densities. …

Stimulated by British experiments, Dr. MacDougall’s staff at ERL tried some methods for controlling and changing the contours of detonation waves. Techniques were developed through which detonation waves were given preselected contours, for instance, made plane or conical, instead of having the usual spherically divergent shape. The use of such controlled-shape waves permitted a much more thorough investigation of the laws of propagation of detonation than was possible otherwise. …

We must end now the account of [ERL] work on the mechanism of the detonation process. It was quite indispensable for many other activities of the Division which had more direct bearing on military applications. However, its nature was such that initially it aroused little interest among the military. Indirectly, the results of this work did affect many military problems by influencing the thinking of personnel working on them. There exist, also, very direct military applications of these fundamental studies. They are of great importance, and it is disappointing that military security prohibits their discussion.

We had to have a second explosive to make the lens, because the lens consists of two media: air around it and the glass inside the optical lens. … The detonation wave, just like in the air, the light velocity is highest. (Well, it is fastest in a vacuum, but it is nearly the same.) So we have to have an explosive which has a very low velocity. And this project I assigned not to the Manhattan District laboratories, who were too busy and did not have enough more organically oriented explosive handling people at Los Alamos. I assigned it to my friends at our Explosives Research Laboratory in Pittsburgh, the so-called Bruceton Laboratory, of which I was the chief until I went to Los Alamos. And it was there that Dr. McDougall, who after the war eventually came to Los Alamos and [stayed] for many years until he retired recently, was the head of all the implosion work.

Linschitz: I took a job with Kistiakowsky at the Explosives Research Laboratory, outside Pittsburgh. We were working on shaped charges on the bazooka and things of that sort. Then, one day Kisty came down and called me out of the lab, and said: “Henry, I want to talk to you about a job, which has a chance of winning the war.” They needed an explosive expert—a supposed expert, I was a kid, I was 22-23 years old at the time—and he [told] me that they were starting to do high-explosives at Los Alamos. He told me about the project, and he suggested that I volunteer. So, I volunteered, naturally.

Heim: It had to be the implosion method that [was] analogous to the shaped charges.

Linschitz: Exactly. They needed people who could handle various configurations of high explosives, and I had been doing more or less that kind of thing at ERL. It turned out, in fact, that what we did [is that] we actually developed the lenses in the final explosion device. And I served on the group that assembled the bomb on the desert test. I put the fuse on.

The basic studies of explosives at ERL between 1942 and 1944 included experiments on the fragmentation of shells, shaped charges, and cavity jets. … Although it was the leading American group conducting explosives research in the early part of World War II, ERL was a relatively small operation, with groups of four to ten people working in buildings only about 16 feet square.

Hiring Kistiakowsky gave Los Alamos direct access to the ERL studies. Several Bruceton researchers transferred to Los Alamos, among them Henry Linschitz, who arrived in mid-November 1943, and Walter Kauzmann, who arrived a month later. In July 1944, the Bruceton program would be joined formally to Los Alamos with the formation of “Project Q,” based at ERL under Duncan P. MacDougall, George Messerly, and Eugene Eyster. MacDougall, who had joined Bruceton in January 1941, was then its deputy research director; as head of Project Q, he would periodically visit Los Alamos to coordinate research at the two laboratories. …

About six weeks after [James L.] Tuck arrived in Los Alamos, [Hans] Bethe and [Rudolf] Peierls began to search for a suitable design for the slow lens component, but without success. The breakthrough occurred shortly afterward when [John] von Neumann proposed a workable design. Elizabeth M. Boggs of ERL had demonstrated a similar lens scheme somewhat earlier, in a memo that MacDougall sent to Los Alamos. (ERL fired a simplified experimental shot soon afterward, and observed some convergence. The progress report refers on p. 5 to “as in Dr. Bethe’s diagram,” indicating instructions from Los Alamos.)

Explosive lens testing was under way in the implosion program by mid-July 1944, when Linschitz fired the first two-dimensional lens model.

Traveling Fund for the Bruceton Research Laboratory: The President [of the Carnegie Institute of Technology] reported that on March 9, 1945, he had authorized the Controller to increase to $3000 the Petty Cash Fund established to provide for traveling advances for members of the Bruceton Research Laboratory. The Bruceton Research Laboratory is administered by the Carnegie Institute of Technology under the auspices of the National Defense Research Committee.

From 1941 to 1945, [George Messerly] served as research supervisor at the Explosives Research Laboratory at Bruceton, Pa. At this laboratory, operated jointly by the Bureau of Mines, Carnegie Institute of Technology and the National Defense [Research] Committee, Dr. Messerly worked on various theoretical and experimental aspects of high explosives and the detonation process.

Two awards were presented to Dr. Messerly by the armed forces for his work at Bruceton on optical studies in explosives during World War II.

MacDougall: Of course, work [on explosives] had been going on at [ERL, in] Bruceton long before Los Alamos had started. The specific program there [at Bruceton] that we called Project Q started only after my visit here [in Los Alamos] May 1st of ‘44, which followed on Kisty [Kistiakowsky] coming out here [in Los Alamos] full time. …

MacDougall: From the best of my knowledge, the explosive lens was actually the idea of a woman, Elizabeth Monroe Boggs, at Bruceton. … (We had a lot of interchange with the British, but exchange of information is never perfect nor complete.) That, I think, was [done] independently. It probably had been done. Once you start thinking about it, it’s not a very difficult idea to come up with. It’s just as far as this country is concerned, the first explosive lenses with Baratol were at Bruceton, but there may well have been some in England before that. That, I just don’t know. …

Hoddeson: Who thought of the design of the logarithmic spiral?

MacDougall: There may have been other people, [but] in this country it was Elizabeth Boggs. Once you set your mind to it, it’s no great thing. I believe that simultaneously in England they also thought of a logarithmic spiral. But the first design and the first experiments were done at Bruceton, and the design was from Elizabeth Boggs. She was basically, I think, a theorist rather than an experimentalist, although basically she was in charge of Messerly’s group there.

Hoddeson: I’m always happy when I see a woman involved in something like this. Could you tell me just a bit more about her? There are so few women in this whole story.

MacDougall: She was very, very capable, I think. … She had studied in England, I know. I forget where her PhD was from. I remember her telling me of some occurrence in England and that she used to be introduced as Miss Monroe.

To the writer’s knowledge, the first efforts to study wave shaping in this country date back to about early 1944 when Elizabeth Boggs and George Messerly undertook to develop a number of ideas with regard to shaping of detonation waves at the Explosives Research Laboratory, Bruceton, Pennsylvania. … They recognized at the outset that a granular explosive was a relatively impractical component to use for this purpose. As a consequence, they undertook an extensive program to search for castable explosives to be used as a low velocity component. Their first efforts included a study of Baranal and Sodatol. They later began to experiment with Baratol.

It may be of historical interest to note that many years ago Cornell University was the scene of another discussion on the problems of shock-to-detonation transition. In 1945 a small group of scientists from the OSRD, the National Research Council of Canada, the Army, and the Navy met here to exchange ideas concerning detonation in explosives. [Gerhard] Hertzberg described to that group some interesting smear-camera records he had obtained concerning the initiation of detonation in solid and liquid explosives. … [Elizabeth M.] Boggs also presented a number of important, and at that time perplexing, experimental observations on the transition from shock to detonation.

The experiment performed by Dr. Herzberg and described by him at the July 17, 1945 Conference at Ithaca, N.Y., in which a transparent liquid column of explosive, initiated at the top surface with a detonator, apparently detonated only a small diameter column of liquid immediately beneath the detonator for some distance beneath the surface of the explosive before the detonation wave expanded to encompass the entire column of liquid, can be interpreted on the hypothesis of detonation failure at an angle to the direction of initiation. … Due to the closing of the Bruceton Laboratory, this will be our only report on initiation phenomena, a field of study which we feel could be profitably further developed as a step toward a better understanding of the detonation process in general.

In 1941 … parallel [fundamental shaped charge] studies were undertaken by… Division 8, National Defense Research Committee (NDRC), Bruceton, PA. The chief NDRC scientists were G. Kistiakowsky, D. MacDougall, S. Jacobs, and G. Messerly. At the same time, E. M. Pugh organized a group at the Carnegie Institute of Technology (CIT). Following the war, CIT took over the NDRC facilities at Bruceton.

Another point which occurs to me is the question of authorship. As you know all of the activities at Bruceton were definitely group effort. Many of the fundamental ideas on plate penetration presented in OSRD Report No. 1338 [“The mechanism of action of cavity charges,” April 12, 1943] were my own but they were certainly influenced by discussion with other members of the staff, and as you know, the report was published under several names [i.e., with Kistiakowsky and Messerly]. For the experimental part, the size of the group participating was even larger. This is a question which I am sure has arisen and is constantly arising in connection with publication of NDRC work, but I am not familiar with the way any of the typical cases are being handled.

The Explosives Research Laboratory, which in peacetime was an experiment station operated by the Bureau of Mines and the US Department of the Interior, was being taken over … and being run by them for the Office of Scientific Research and Development [OSRD] … I was a member of a small group [there] that was headed by a fellow named George Messerly …

George Messerly had designed a rather interesting type of camera, the purpose of which was to study explosions—detonation rates and so forth—by photographing a moving trace. When a detonation passes through a solid explosive or even a liquid explosive, the wave produces luminescence at the front of the wave, sometimes diffuse, sometimes very precise. This camera had a rotating drum and a slip which enabled you to track that moving bang stripe – whatever you want to call it – to track a point on it and create a record on moving film, which if you knew the rate at which the film was moving past the slot, you could calculate the rate at which the detonation was moving in the explosive. That was basically the element behind that. It also permitted for the study of certain other phenomena like the shape of shock waves, where the phenomenon itself produced some sort of luminescence, or could be illuminated, and whereby focusing on just a piece of it, tracing the amount of it that you can see through the slip over time by moving the film passing. We had a variety of things that we could study that way. Every time we wanted to take a picture, it involved setting up the bombproof. This was all done in an underground cavity, where the explosion could take place without damaging anything. You had to mount the film in the camera. You had to set all the parameters. Then you got the film and you had to measure the trace on the film and calculate the rate and so forth. Well, I did some of the theoretical work that attempted to interpret what were the experimental results we were getting.

One of the things we did… Well, when I first went to the Explosives Research Laboratory, there were perhaps a dozen of these individual working groups, who were physically separated from another. We were already engaged in work that’s classified as confidential, so we were under instructions… We didn’t fraternize as much as we might otherwise, because each group was supposed not to talk about what it was doing to another group that was doing unrelated work. There was an overall director to the laboratory, who was responsible. When we first went there, we were primarily just studying the detonation rates in classical or traditional explosives, which are used not only in bombs but in torpedoes. The question [was]: “How fast does a detonation move from the back of the torpedo to the front of the torpedo?” One of these other things we studied [was] the way in which the casings of torpedoes break. They tend to peel off like banana peels. … We were working on those things.

Then, there was a stage. I began there in the summer of ‘43 and I left there in the summer of ‘45. About halfway through that time the Manhattan Project was gearing up and the Los Alamos laboratory was busy preparing the first a so-called atom bomb. One of the problems that had to be solved with the development of an atom bomb was that it had to be portable in a safe condition yet capable of being detonated accurately. … The problem was to bring the critical mass together in a controlled way. That is to say, not inside the airplane that was carrying the bomb, but somewhere outside it at a time that was appropriate to the target. We had developed in the course of the work in our particular group, techniques for shaping detonations. That is to say, in the ordinary course of events you started detonation in an ordinary explosive at one point. You set it off with a detonator and the wave that ensues from that is approximately spherical, like ordinary radiation. We, however, had needed to produce as nearly as possible flat detonation waves. We had needed to do that because we could only put a limited weight of explosive into that bomb-proof with that camera, without blowing up the camera. If we spent a lot of our explosives getting the wave from being a small circle to being a large one so it was nearly flat—so that we can study a flat wave—we would never have gotten to the part we wanted to study. So, we had been busy devising ways to get from a point detonation to a flat wave.

I won’t go into all the details about that, except in that [work] we had observed that detonation waves follow somewhat the same rules that light follows, in that you can shape the front by putting it through something like a lens, and lenses depend on the difference in density between the two mediums. If the shape of the interface is not just a straight line or a plane surface, then the way in which the light rays come out as a wavefront out of one medium with one another will be changed. We used the same principle because we had solid castable explosives that were of different detonation rates. So, we had been able to do that. The upshot was that when they came to us with a problem…

This is one of the interesting problems of security. They didn’t really want to tell us what they were going to do with the product they wanted us to design. They told us what they wanted us to do. If we had really known what their end product was supposed to be, we would have gotten there faster. What they wanted to do was to cast as a hollow sphere of explosive and coat the interior with the fissionable material and then cause what they called an implosion, that is to say an explosion from the outside going inward toward the center, which would have the effect of collapsing that shell of fissionable material that coated the interior of the hollow sphere of explosive. … Their idea of how to do that was to take the sphere of cast traditional explosives and attach to the outside of it a large number of detonators.

The whole thing would look like a permanent wave machine, if you’ve ever seen one. In the old days when women had permanent waves, they had lots and lots of little rollers put in their hair with electric wires coming out of them. They were heated. … Nowadays, you just do it chemically, but in the early days they heated each individual curl. So, when you were having a wave, you were sitting under this thing with the wires going up. Well, it would have looked rather like that.

The problem that they presented us with was that in order to have all of those detonators go off at the same time you had to have Primacord, which is a special fusing device. Primacord is a hollow plastic casing about quarter of an inch in diameter, which is filled with solid explosive—powdered explosive which is packed. The detonation rate of Primacord is fairly well known. You detonated at one end—it’s a fuse—and the explosive inside the Primacord travels at a fairly predictable rate, so that you can calculate how long it’s going to take for something to get from one end of the meter-long cord to the other, although you would scarcely see it with your eyes. Their idea was to have lots and lots of trails of Primacord for each of these points and to detonate the Primacord in one central place. They needed to have very reliable Primacord and they wanted us to improve the reliability of the Primacord and study it. We eventually used an entirely different technology, which was to design an explosive lens which was composed of two pieces of explosive cast together but having different detonation lengths and having a curved interface. The mathematical formula for that curve was such that when you started the detonation right up here, you produced a straight detonation in the initial explosive but that had the effect of setting off a curved detonation in the second explosive, like focusing light. That was eventually what was used. It was designed to produce an implosion, that is to say, two hemispherical detonation waves, which converged on this sphere and produced the collapse. …

Even though we had not been allowed to know very much about what was going on in Los Alamos—it wasn’t even mentioned by name, it was just that place out there and we didn’t know exactly what it was, but definitely some of our senior people went out there… Although we had not been told very much about what it was we were doing, and why we were doing it, we had enough knowledge of it so that when that bomb was dropped, I knew that that had been the target against which we were working. By the target, I mean the accomplishment towards which we were working. …

There was another interesting episode. Because during the winter and spring of ’45, the American troops were moving across Europe, … the Americans were capturing research equipment and research records in German, and they had sent back quite a lot of confidential and secret papers that had been written in the German Laboratories. … These had been sent to a repository in … Washington. They would circulate to various American laboratories that were working on these kinds of things lists of the papers that had been found in the occupation there. We were supposed to be able to request and obtain copies of papers that we thought were immediately relevant to our work. … I looked at this list and I selected three or four papers that I thought we could use. So, a letter went forward from the director of the laboratory requesting these things. We got a letter back, which said that before they went through the expense of their budget … duplicating this material, they thought that somebody from our laboratory should come at our expense—all on the government, on our budget—to look at the material to see whether we really wanted it and whether it was really worthwhile for them to [copy] it. In other words, we should spend $125 before they spent $25 to see if it was worthwhile.