Unable to convince Fermi that this was the case, Szilard set out on his own. He obtained permission from the head of the Physics Department at Columbia, George B. Pegram, to use a laboratory for three months. To fund his experiment, he borrowed $2,000 from a fellow inventor, Benjamin Liebowitz. He wired Frederick Lindemann at Oxford and asked him to send a beryllium cylinder. He convinced Walter Zinn to become his collaborator, and hired Semyon Krewer to investigate processes for manufacturing pure uranium and graphite.