Final answer:
The water climbing up a capillary tube is an example of capillarity, specifically due to the property of adhesion, where water molecules are attracted to the glass walls of the capillary tube, causing capillary action.
Step-by-step explanation:
The phenomenon of water "climbing" up a capillary tube that William noticed is an example of capillarity, which is a consequence of the water property called adhesion. In this context, adhesion refers to the attraction between water molecules and other substances, such as the glass walls of the capillary tube. This attraction draws the water up the tube, defying gravity. The water molecules adhere to the tube walls more than they do to each other and this allows for the water to rise within the narrow space of the capillary tube, displaying what we know as capillary action.