The yellow model is a standard drain pipe. A quarter of the real size, it was made on behalf of W H Knight of the Hygiene Referendum. This one was originally from a set of twelve models that were used to teach and assess officials involved in public health. Hygiene and cleanliness were a major focus for public health officials, particularly in light of the germ theory of disease which had been established a few years previously. A full set of models cost over £3. It is shown here with a brown intercepting trap drain from the same set (1896-61/4/1).