CRICK, Francis (1916-2004). Autograph letter signed (“Francis” and also “F.H.C. CRICK” in return address), to Leonard Hamilton, 23 April 1956.

One page, 240 x 197mm. On Cavendish Laboratory airmail stationery, Department of Physics, University of Cambridge (a little unevenly opened). Stapled to a carbon-copy of Leonard Hamilton’s typed reply, dated 26 April 1956.

Francis Crick prepares for his American trip in the spring and summer of 1956. Crick’s two major collaborators at this time were both American: Alexander Rich (1924-2015), with whom he proposed a molecular structure for collagen; and James Watson (b.1928) with whom he continued working on the structure of small viruses. To quote: “Just to say that I’ll be over very early in May … and am looking forward to seeing you all again. Shall be around New York for about a week (I have places to stay), than to Alex at Bethesda, and then conferences in June & July.” It was in this time that Crick was building up to his “Central Dogma,” the axiom that DNA and RNA specify protein, but that protein can never specify either—first outlined in his paper “Ideas on Protein Synthesis,” October 1956.