Franklin and Wilkens experiments (6h 21min, jan 1, 1944 y – 16h 29min, may 24, 1958 y)
Description:
 Wilkins began using X-ray diffraction  to produce images of the DNA molecules. 
Franklin also helped by using two different fibers of DNA, a hydrated one and a dry one. Then she deduced the basic dimension of DNA strands. She also discovered that the phosphates were probably outside of the helical structure. 
Added to timeline:
Date:
6h 21min, jan 1, 1944 y
16h 29min, may 24, 1958 y
 ~ 14 years