A $25-$cm$-$long massless spring is suspended from a pivot. A ball attached to the spring's lower end is initially at rest. The ball is gently pushed slightly to one side and then swings as a pendulum at the end of the spring with a period of $1\mathrm{.}6$ s$.$ The ball is stopped, then pulled down slightly and allowed to oscillate vertically. What is the period of oscillation?