Reposted by Ci Ji (CJ) Lim
Yes, she knew it was a helix and even concluded there were 10 bp/turn, with bases separated by 34 Å. For an explanation of how you can deduce all that (and more) from these patterns, see youtu.be/2tMuMRY1oDo?...
youtu.be
Photograph 51 explained
YouTube video by Cynthia Wolberger