1.
The Perpetual Calculator: Or, Time's Universal Standard. in Three Parts. ... by R. Wetherald...
by Wetherald, Rowland, Rowland...
ISBN: 9781379293811
List Price: $23.95
2.
Perpetual Calculator : Or, time's universal standard. in three parts... . by R. Wetherald, P...
by Wetherald, Rowland
ISBN: 9781140678151
List Price: $21.75