A millrace is the channel, usually cut or lined, that carries fast-moving water to drive a mill wheel, and the fact that one is recorded here points to a small but functioning industrial operation that has since been entirely absorbed into the urban fabric of south Dublin.

The first edition OS six-inch maps for Ireland were surveyed in the 1830s and 1840s, capturing the country at a moment before large-scale suburban expansion had begun to swallow the working landscape on the edges of towns and cities. At that moment, the area south of Rathmines retained enough of a rural and light-industrial character to support a dye works, and the Dartry Dye Works appear to have drawn their water power directly from this millrace. Dyeing and textile processing operations of this period typically required both a reliable water source for the dyeing process itself and, where possible, mechanical power for associated tasks, making a riverside or channelled location essentially a requirement rather than a convenience.

The precise line of the millrace is no longer visible on the ground, and the Dartry Dye Works themselves have long since disappeared beneath later development. Anyone curious about the site would do well to consult a digitised copy of the first edition OS six-inch map, which is freely available through the Ordnance Survey Ireland historical map viewer, and to overlay it against a modern street map of the Dartry and Rathmines South area. The exercise of tracing what is now a road or a garden boundary back to a working water channel is, in itself, a way of reading the older landscape beneath the current one.