An early unsigned marine clock movement that is firmly believed to have belonged to one of the timekeepers developed by Alexander Bruce in collaboration with Christiaan Huygens in the 1660s. The movement was later converted into a weight-driven domestic longcase clock. The only other of these movements known to have survived is signed by Severyn Oosterwijk and was shown in the NMM's 2014-15 exhibition, 'Ships, Clock and Stars: the Quest for Longitude' (LOA1568).