This brass bound teak box looks as if it's a thunderbox or commode, and although that was a secondary use its main purpose was a bidet.
It was designed by Andrew Paul, a member of the Dublin Royal College of Surgeons, and the author of a book entitled Observations on the Diseases of the Lower Bowel, first published in 1840.
Paul argued that to stoop over an ordinary bidet, which was essentially an elongated bowl on legs that could not bear much weight, was not conducive to the treatment or cleaning of the area in question. Much better to sit and have more comfort. His bidet was illustrated in his book and he described it as a luxurious piece of furniture. As can be seen there is a pump to the side with ebony handle. This sprays water up through a fountain to the centre of the decorative porcelain bowl, which is then recycled. The fountain had the option of four different rose heads, two of which remain and are stored in the side door. The seat has a turned cover and the underside of the lid has a pressed brass plague noting Andrew Paul Patentee. Mid 19th century.
Size closed is given.