It was December 15, 1945, and Ed Purcell had just spent the night in a shed outside the physics building at Harvard University. His vigil was to keep a watchful eye on a generator which was supplying the current for his electromagnet. Immersed in the field of this magnet was a piece of paraffin, dense with protons, which he figured had to be polarized in the field all night in order for his experiment to work. Now he was ready to throw the switch.

His goal was to show nuclear magnetic resonance. Columbia University professor, I. I. Rabi, winner of the Nobel Prize for his work in molecular beam magnetic resonance, had discouraged him from doing this experiment by telling him that another scientist, Cornelius Gorter, had tried the very same thing without success. But Purcell went on with the experiment probably thinking that an error could have been made by Gorter by not waiting long enough to polarize the sample, since Purcell's collaborator Henry Torrey had calculated the time required to polarize the sample might be hours.

Joined by his collaborators Robert Pound and Henry Torrey, the electronics was turned on to begin the experiment. The rheostat was adjusted to sweep the magnetic field through the values they calculated would show nuclear magnetic resonance. Nothing happened. They decided to increase the current on the chance that their calculations were in error. Still nothing. With the only other option being to turn everything off and go home, they decided to take the current up as high as it would go to see what would happen. As they slowly decreased the current from its maximum value, they saw their meter suddenly jump. Could this be what they were looking for? Sweeping the current a few more times convinced them. They had just observed something that no man had ever seen before - Nuclear Magnetic Resonance.

Note: Only a couple weeks later, in early January 1946, Felix Bloch along with collaborators Martin Packard and William Hansen at Stanford also demonstrated nuclear magnetic resonance but by an entirely different method and without the knowledge of the work of Purcell's group. Purcell and Bloch shared the Nobel Prize in Physics in 1952.

To learn more about the history of Nuclear Magnetic Resonance read the book The Pioneers of NMR and Magnetic Resonance In Medicine: The Story of MRI by J. Mattson and M. Simon.