The After Steerage was where the Firing Battery was located. The battery was intended to provide the current to detonate the torpedo (mine) that exploded prematurely on the 5th of March 1881.Interview with Gunner James Tubb,
"How far was the binnacle stand from the battery? - The battery was down below in the after steerage."
"And the distance from there was fourteen feet? - "Fourteen feet horizontally & six perpendicularly."
28 March 1881 Torpedo Accident Report,
mouseover battery and red dot.