What Observations Did Harlow Shapley Make That Indicated That The Sun Is Not At The Center Of The Milky Way?

What Observations Did Harlow Shapley Make That Indicated That The Sun Is Not At The Center Of The Milky Way? Since the clusters assumed a spherical arrangement, it was logical to conclude that they would cluster around the centre of the Galaxy; from this conclusion and his other distance data Shapley deduced that the Sun