bell-topper

Etymology
From, referring to its shape +

Noun

 * 1)  top hat; chimney-pot hat
 * 2) * 1903, William Craig (of Invercargill, N.Z.), My Adventures on the Australian Goldfields (page 11)
 * “Now, you long ghost with the bell-topper, what did you pay for that coat? It's a Houndsditcher!” The sally was greeted with laughter from all who heard it.