This chart is particularly interesting because it shows the little-known Rockville Navigation, the network of small lakes and canals up the Grange River. The book (written in 1952) does not mention the Rockville. Hugh Malet, in "In the Wake of the Gods", describes a small-boat trip on the system; the navigation is mentioned briefly in an early Shannon Guide and it is shown on early Ordnance Survey maps, but it seems to have been forgotten since Rice and Malet.