"Bacchus in Vacuo is an image mounted on a small brass barrel, which has a partition in the middle dividing it into two parts, one of which is open to the pressure of the atmosphere, while the other is closed, containing a quantity of water and air. A glass tube communicat- ing with the water in the closed end, passes up into the mouth, and down the neck of the image into the open end of the barrel. A small sheet rubber bag is concealed under the dress and contains a small portion of air which expands as the air around is rarefied". From the 1844 Catalogue of Pneumatic Instruments, published by N.B. and D. Chamberlain.
The cut from the catalogue at the right shows how the apparatus is placed under the bell jar of the vacuum pump.
