Donald F. Hornig

Reminiscences of World War II and Los Alamos

First Published in Little Compton Remembers World War II, 1945-1995

A Project of the Little Compton Historical Society, August 1995              

The reader should be warned that these are probably the self-inflating recollections of a youth who was 21 years old when the story started and 25 when it reached its dramatic conclusion. It began in the fall of 1941 when our research group at Harvard University gave up its work on infrared spectroscopy and molecular structure to do research on high explosives; it concluded at the first atom bomb test at Alamagordo when I sat beside the first live atom bomb on the top of a 100 ft tower while lightening flashed and thunder crashed all around me. But more on that later.            

Our start was modest enough. We developed piezoelectric gauges (which generate an electrical signal in response to changes in pressure) and amplifiers to measure the shock waves produced in the surrounding air by an explosion. It seemed pretty sophisticated then to measure things that happened in millionths of a second but by modern standards our methods were hopelessly primitive. We tried our equipment out by setting off small explosions in a vacant lot in Cambridge until the neighbors complained and the police intervened. After that we moved to Nonamesset Island, just off Woods Hole, Massachusetts, where we could deal with bigger charges.

Along the way I learned something about how governments work. In the winter of 1941 I was appointed to act as a liaison to the British Ordnance Laboratory in Swansea, Wales, which was under heavy air attack at the time. I collected my gear and on the black nights a few days before I was to sail on a 9000 ton freighter I couldn’t help thinking about the stormy Atlantic in January and all the submarines out there. I needn’t have worried because the day before I was to sail the venture was cancelled. Why? Because the two governments could not agree on who would pay my salary.

The pace picked up in 1942 when the British began to use one ton bombs on German cities, the biggest ever until then. Naturally the US Air Force quickly concluded that they needed two ton bombs. The Harvard group, along with Princeton, the Naval Ordnance Laboratory and the Aberdeen Proving Ground were asked to help choose the best explosive and to insure that the bombs were successfully detonated. That isn’t as easy as you might think since when a lot of material is exploded it is likely to scatter some of it around without going off.            

The tests were scheduled with great urgency. Professor E. Brisht Wilson, Jr., my mentor, gave up Thanksgiving with his family. I had to give up Thanksgiving with the parents of my new friend. Lilli (now my wife), who came up to Boston, I presume, to check me out. I met her parents in South Station when they arrived and I departed. The next morning Prof. Wilson and I arrived in Aberdeen to find that the laboratory in which we were to work hadn’t been built yet. Nor had anyone made reservations at the Officers Club for us to have Thanksgiving Dinner.            

Nevertheless, we set to work in an area at the Proving Ground called Abbey Point. The bomb was to hang from a pole in the middle of a sea of knee deep mud. Around the pole we laid our cables, gauges and amplifiers. Our base was a bomb proof shelter a short distance from the bomb. In short order the Army found out why they didn’t want me as a soldier; I committed a series of unmilitary gaffes. As the commanding general was coming down the steps to inspect progress in the bombproof I was coming up the stairs in a hurry and accidentally tackled him. When the colonel in charge heated a can of soup in the coal burning stove which warmed the shelter I forgot myself, raised the lid, and disposed of the ashes from my cigarette into his soup. As the Princeton team loaded two or three yards of film into the rim of a bicycle wheel which was part of their high-speed camera I waited impatiently in the blacked out room and finally lit a match while they frantically clasped the film to their chests.  

I saved the best until the end. After the bomb was hung from its pole and we had all checked out our instruments I discovered that someone had taken my spare battery. A quick check ascertained that the battery had been used on the firing line to the bomb. Since any battery would do for that purpose I replaced my fresh battery with another. The moment came to fire. “Is Princeton ready?” “Princeton is ready,” and so on through the groups. Then the command — “fire.” Nothing happened. Now what to do with a live bomb dangling out there from a pole. I had an idea and dashed to the firing station with my good battery and said “try this.” It worked and the bomb went off. For a moment I was a hero; only later did a cloud of suspicion descend on me.  

One other episode surrounding that first test deserves mention. The bomb hung from its pole, and beneath it members of the various groups were working on their instruments when there was a long whistle and an explosion in the mud beneath the bomb. About thirty seconds later it was followed by another. The military officers among us recognized it as artillery fire — but from where? Frantic telephone calls failed to resolve the question and as successive shots landed among the group, and frighteningly close to the bomb, we beat a most unsoldierly retreat — except for Prof. George Kistiakowsky, an old veteran, who observed “Well, it all goes to show that artillery is not effective against personnel.”

It turned out later that the shots came from a tanker in the Delaware river which was on its way to England and wanted practice for its gun crew before facing submarines. They mistook our bomb for a target since it was in an area labelled “target area” on their map.  

The twelve shots we carried out at Aberdeen Proving Ground provided the experimental material for my Ph.D. thesis which was completed in the summer of 1943, not long after I married Lilli. Thereafter I got my first job at the Underwater Explosives Research Laboratory in Woods Hole, Massachusetts. Lilli and I settled in, bought a half interest in a 45 ft. yawl, and expected to make our contribution to the war there.  

That expectation was interrupted by a little comic opera. My boss, Prof. Wilson, came up to me one day and in a low voice invited me up to the attic for a chat. “Hornig, how would you like another job?,” Wilson asked.   “Have I done something wrong?”   “No,” Wilson said. “It’s just that you’re wanted elsewhere.” Where, he wouldn’t say; nor who wanted me, or for what purpose. All of these things, he said, were secret.   “Is the job in the Northeast, the Southwest, the Southeast or the Northwest?” I asked.   “I can’t tell you that,” Wilson replied. “Well then tell me whether this is a matter of duty. I trust you and will rely on your assurance,” I said.  “No, that is something you will have to decide for yourself. Why don’t you go home, talk it over carefully with Lilli, and tell me in the morning what you decide.”  

I went home to discuss the situation with my wife, who was also a chemist midway through the research for her own Ph.D. at Harvard. We couldn’t find much to discuss other than that this would cut her work short for a while. We also speculated about the meaning of these mysterious goings-on but had no clues. We agreed, “why should we buy a pig in a poke?” The next morning I told Wilson that unless I knew more the answer was “No.”   Not more than an hour elapsed before the intercom blared: “Telephone call for Dr. Hornig from Washington.” On the line was Dr. James Bryant Conant, President of Harvard and head of the Office of Scientific Research and Development. He told me how unpatriotic I was and reminded me of the pictures in all the post offices which said, “Uncle Sam is pointing his finger at you.” I thought that was pretty corny and I was angry.   Shortly thereafter the intercom blared again — this time the call was from Santa Fe. It was from one of my favorite Harvard Professors and a great scientist, George Kistiakowsky, who I have mentioned previously. He said he was setting up a research group in a new laboratory and needed me, for what he wouldn’t say. He also said there were lots of jobs for chemists on the mystery project and that Lilli would be able to find good work there. That did it.

We sold our share in the boat and bought a used car. A few weeks later, without telling even our closest friends we were leaving, much less where we were going, we packed up our ancient Ford coupe and headed for 109 E. Palace Avenue, Santa Fe, New Mexico, where we would receive further instructions. There we were directed to a place high on a mesa at the base of the Jemez mountains whose name I had never heard before: Los Alamos.  Despite its beautiful setting Los Alamos was a drab and dusty army base.

Nonetheless, what we learned was electrifying. The project was producing a synthetic element, Plutonium, in Hanford, Washington, which would be the basis for a bomb with the explosive equivalent of 20,000 tons of TNT. Of course there were problems. At that time, May 1944, a few grams of Plutonium had been made and purified, whereas ten or twenty kilograms would be needed for a bomb. Furthermore, there was a rough conceptual design for a weapon but progress was very preliminary. Still, with a focus on Hitler and Nazi Germany there was a sense of very great urgency.    

For me, though, Los Alamos was a great disappointment. I had come as an explosive expert who would measure the effects of the atomic bomb. But those critical bomb tests were months and possibly years off and I had no apparent immediate role. To sit at a desk and plan was demoralizing. That changed at one of Dr. Robert Oppenheimer’s staff meetings at which he opened difficult problems for discussion. Oppenheimer talked about a central problem: how to focus the shock wave from an explosive shell on the plutonium core of the bomb. We had to initiate a set of sixteen explosive lenses within one ten-millionth of a second. The only idea at that point was to use an explosive switch to initiate them all at once. But such a device could never be tested since the explosion would destroy it. At that point I had a sudden insight as to how this might be done — with a set of triggered spark gaps. I proposed this to Oppenheimer and he immediately responded by asking me to develop the idea. I put together a team and we went furiously to work.  

By fall I thought we had the fundamental problems in hand but most of my colleagues, including Kistiakowsky, the big boss, were very skeptical as to whether this critical step could be entrusted to the work of a 24 year old. By October a decision as to the route we would follow had to be made. In her book “Critical Assembly: A technical history of Los Alamos during the Oppenheimer years, 1943-1945” Lillian Hoddeson says of this decision: “at this point the issue of which switch to use in the firing circuits was also unsettled. Although Kistiakowsky strongly favored the explosive switch, Hornig boldly objected, arguing strongly on 9 October against the explosive switch and in favor of the spark-gap switch that he and his co-workers had been exploring for the past several months.”

The decision was made in my favor and from then on we worked, not only to insure the reliability of the spark-gap switches, but to build a reliable firing unit, the X-unit, incorporating them, for the atom bomb. From then on I was on the spot to produce units in time, but by late spring of 1945 we had a few commercially manufactured X-units available.   The test of the first atom bomb was scheduled for July 16, 1945, at a site named Trinity in the Jornada del Muerte (Journey of Death) near Socorro, New Mexico. We weren’t ready but President Truman was meeting in Potsdam with Stalin and Churchill so we had to be. Troubles persisted until the last seconds. In a test on July 9th the X-unit fired prematurely and although the causes were understood it made everyone very nervous. On 14 July the assembled bomb was hoisted to the top of the 100 foot tower on which it would be detonated. That same day a dummy X-unit which was being used in the intensive final testing failed. I was in trouble, but by the next morning it was determined that a glass spark-gap switch which had been designed and tested for a few firings had shattered after about 300 tests. The decision was made to proceed but the confidence level was low.

On July 15th it was my job to attach all the firing cables to the X-unit of the real bomb and this I did in the late afternoon. The tension by that afternoon was enormous. In addition, the weather looked bad and the forecast was that it would deteriorate. The orders from Potsdam were to proceed anyway. Against this background Oppenheimer held a meeting at about 6 p.m. at which Bainbridge, Kistiakowsky and I were present. He was terribly worried at the possibility of sabotage and decided that someone who understood all the details should stay with the “gadget” until we were ready to lock it up for firing. We agreed to take turns and (I suppose) as the youngest my turn came first. Soon a violent thunder and lightning storm enveloped the site, but at 9 p.m. I climbed the 100 foot ladder to the top of the tower.  

At the top I sat in a twelve-by-twelve ft. metal shed. At my side was the bomb — ready to go. Lightning was flashing and thunder was crashing all around me. I kept picturing this giant storm setting off the whole Trinity blast and wasting the national supply of plutonium as well as all the efforts of the preceding months. There was also me to consider, but the metal tower was so wet and so well grounded that it didn’t seem likely that if lightning struck anything would happen. And if it did death would be instantaneous and I’d never know. So I sat on a folding chair beneath a naked sixty-watt bulb, reading a cheap paperback novel, DESERT ISLAND DECAMERON, and from time to time getting philosophical about the monster beside me. My happiest moment came when the telephone rang and I heard Kistiakowsky saying: “Don, you can come down now.” No one went up to replace me.

I still had a job to do. As the proprietor of the firing unit I would man the one switch which could stop everything if a problem arose: the “chicken switch.” I was stationed just inside the door of the control bunker, 10,000 yards south of Ground Zero. My console included four meters attached to the X-unit and a number of red lights. At minus thirty minutes everything went on to an automatic timer. I had the only override. At about minus five minutes a very nervous Robert Oppenheimer worried whether the tension might overcome me but there was no time for discussion. I just stared at the console, holding the switch that would cut the connection between the bombproof and the tower if anything went wrong.

Nothing went wrong. Up to the moment of the blast my only thought was: “Your reaction time is a half-second. Don’t blow it.” I was very intent on doing my job. At the moment of the blast at 5:29 a.m. all the needles dropped to zero. There was a brilliant — no, over- whelming — flash of light. I stepped through the door of the bunker and saw a luminous, billowing fireball – swirling clouds of peach, blue, green-going up and up. That was the end of the war for me and fact the war did end three weeks later. My immediate reaction was to be terribly tired; I had scarcely slept for forty-eight hours. My second reaction was: “We’ve really opened a can of worms, haven’t we.” And for years I then worked on the proposition: “Where do we go from here?” In fact, the world changed forever.  

— Donald F. Hornig

For More About Dr. Lilli Hornig

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