Ferdinand's ridiculously ornate covered carriage mounted on Simoom's back, with curtains and a steering horn.
The howdah is the ridiculously ornate covered carriage strapped to the back of Simoom, owned along with the rhinoceros by Sir Ferdinand. Kibben has to grunt and heave to get Princess Donut positioned inside it. It is steered by a horn — push forward to go, pull back to stop — and screened by fabric curtains that Carl lowers as they ride out of the castle to face the enemy army.
Donut spends the march complaining loudly that she can barely see through the curtain, then finally rips the screen veil away to ask whether the orc across the field is crying.
A ridiculously ornate, covered carriage rig mounted on a rhinoceros's back, fitted with heavy fabric curtains and a steering horn.
Donut's mobile parlay throne and cover during the ride out.