 Furberg's results had also provided the correct orientation of the DNA sugars with respect to the bases.During their model building, Crick and Watson learned that an antiparallel orientation of the two nucleotide chain backbones worked best to orient the base pairs in the centre of a double helix.Crick's access to Franklin's progress report of late 1952 is what made Crick confident that DNA was a double helix with antiparallel chains, but there were other chains of reasoning and sources of information that also led to these conclusions.