Numerical tables are important objects of study in a range of fields, yet they have been largely ignored by historians of science. This paper contrasts and compares ways in which numerical tables were used by Galileo and Mersenne, especially in the Dialogo and Harmonie Universelle. I argue that Galileo and Mersenne used tables in radically different ways, though rarely to present experimental data. Galileo relied on tables in his work on error theory in day three of the Dialogo and also used them in a very different setting in the last day of the Discorsi. In Mersenne's case they represent an important but so far unrecognized feature of his notion of universal harmony. I conclude by presenting a classification of different ways in which tables were used within the well-defined disciplinary and temporal boundaries of my research. In doing so, however, I provide a useful tool for extending similar investigations to broader domains.