*** w50 7/15 p. 217 par. 3 Postwar Enlargement of the Theocratic Organization ***
So the enemy seized upon it as part of their proof that the Society’s president and other members of the organization closely associated with him were guilty of sedition against the government, and Brother Rutherford and seven others were railroaded off to federal penitentiary in the spring of 1918, under sentences of 80 years in prison, and without benefit of bail for their freedom till appeal to a higher court should be effected. After nine months in the penitentiary bail was granted them on March 21, 1919, and they were released.
So, apparently, 3 1/2 days = 9 months. According to other sources, "spring of 1918" = "June 20, 1918" (w51 7/1 p. 409 par. 4) or 274 days. Thus, each "day" of the symbolic 3 1/2 days = 78.28571428571429 literal days.