Dre Dorothy WrPnch,
Physics Department,
Smith College,
Northampton, P:ASS
USeA.

Dear Dorothy,

Thank  ou so much for your letter and reprints and for

my getting to America this summer  but I certainly hope to
come again some time, and to visit you in rather less of a
rush*
ence in Srussels in August) and spendfng my holiday on the
Continent after that,

your very E ind Invitation* I am afraid there is no chance of

This year I sihall be going to the Biochemistry confer-

  I enclose the numerical values of the Patterson, The ae-
wacy its, of course9 considerably lover than for a crystal
beuiauae of the difficulty of measuring Intensities on very
dl fibss-dia ram9 havlng peaks of various shapes an8 sizes*
(The large, unw 8 edly numerical scale Is simply because It wa8
easier to get the figures copied as they were than to reduce
them).  The origin peakahas been adad in, assuming it to be as
fur a uniform density rod of radius 75A, and using the first two
observed equatorial maxima to obtain the
worksd out the absolute scale, but you c it approximate-
ly from the fact that the origin peak is      a nutzit cell" in

f: have not

the form of a disc of radius 75A and height @A surrounded by
wlst ea-

X thlnk there is now very little doubt that the principal

nan-axial periodicity of TMV protein is &&kea&, there being
*+l units in 3 turns of the helix,
cell Impossible,  f have no Information at present about the
3-d5nonsfonaI distribution of any rsfzections, but I believe that
the strong 11A reflection$ on the 2nd and 7th layer-llnss are due
to structure     the protein subwnit, and therefore have ro-
tatioura2 apetry of a higher order,

You have probably seen by now the 3-d3Jn~~ional Patterson of
DNA In Acta, I will ask Gosling to send you a set of reprints of

This makes a hexagon unit

all our IDEA papers+

With best wishes,

YOU3%,