How it All Fits Together
While the water expands as it warms, the blown-glass spheres' sizes remain
Consider the case where the temperature rises from
72° F to 74° F.
At first the sphere is lighter than an equal volume of water. As the temperature increases,
the water's density decreases. Finally, the weight per unit volume of the sphere is greater
than that of the surrounding water and the sphere falls to the bottom.