This is a series of three articles on a common theme, toy brass locomotives made in the second half of the 19th century. The approach is close object analysis and, being written for specialist collectors, experiential and connoisseurial. All three locomotives discussed are rare for being inside-cylindered, a fact that puts them at a premium in the collecting world. 'Converted' considers a rebuilt locomotive. 'Where There's Muck -There's Brass' considers a comparatively large locomotive requiring some intervention. 'Good Things Come In Small Sizes' discusses its near opposite.