This deportment chair is also known as the Astley Cooper Chair. It was the invention of Sir Astley Paston Cooper (1768-1841), a surgeon and anatomist. He developed it to correct faulty posture in children: the design of the chair forces children to sit on it correctly. Good posture meant keeping a straight back and upright head, and moving in a dignified and elegant way. It was considered very important, partly for medical reasons but also for discipline.
These chairs were often found in the corner of a Victorian classroom or nursery. When children were naughty it was seen as a good form of punishment. The child would be made to sit on the chair for a long period of time. It would have been quite uncomfortable and having a small seat there would not be space to fidget or slouch. They would have to stay in a bolt upright position, if not they would have fallen off.