What is the tip of an umbrella?

The tip of an umbrella is the spike that was originally on all umbrellas but not parasols.

The spike is centred on the outside of the umbrella at the point where all the 'ribs' meet. The purpose was so that when the umbrella was placed in an upright position to dry, IE when the 'tip' was on the floor, the water would not accumulate in the material but run down the 'tip', drying the whole umbrella.