19th August, 1974
Dear Mr. Poggenpohl,
This is in reply to your letter of 13th August about the painting that you are planning to commission from Jean Leon Huens of Jim Watson and myself.  I am afraid it is quite impossible to obtain the original model as all the parts were dispersed long ago as we no longer use models of this type.  I myself, like Dr. Watson, have no particular preferences.  In the circumstances I would suggest it is very much easier for you to use the coloured model to which you refer in your letter.  There is, however, one point which I think I should draw to your attention.  Naturally when people build models of DNA they only build a short length as otherwise the cost would be prohibitive.  The photograph that you sent me displays about two turns of the double helix.  However, even the smallest DNA molecule is very much longer than that and the DNA molecules in higher organisms can be extremely long, some being over a million turns or more in length.  It might be sensible therefore if the model is to appear in a painting, if the artist were instructed to make it appear endless in the sense that the beginning and the end of the model should be outside the frame of the painting.  The majority of the population of the world, including Salvador Dali, is under the impression that DNA consists of about a turn and a half and I think that Geographic might do something to correct this misapprehension.  There is one final small point which I hope you will not mind if I stress.  I have never been knighted.  I do not mind people occasionally addressing me as Sir Francis Crick in a letter but it would cause me infinite embarrassment if this title were to be used in Geographic.  May I ask you personally to take particular care that some well-meaning person does not slip it in at the right moment.  Perhaps you would be good enough to bring this point to the attention of other people working on this article in the magazine.
Yours sincerely,
F. H. C. Crick