The National Archaeological Museum (MAN) displays an important collection of scientific instruments from different periods, some of which are of extraordinary value, such as the Roman clock of Belo, the Andalusian planispheric astrolabe of Ibrahim ibn Said al-Sahli, the great astrolabe of Gualterus Arsenius (said of Philip II) and the Rabdologic abacus. There are other objects of interest in the collection where art and mathematics merge. The objects in the collection of Professor Manuel Rico y Sinobas (1819 – 1898), physicist and doctor, are not of the same quality as those mentioned above, but are of interest. The theodolite/astronomical clock by Gualterus Arsenius, which would be an excellent piece if it were complete, is unique of its kind. The collection of 18th-century pantographs is very remarkable. Among the carpenter’s and navigator’s slide rules there is an extraordinarily rare square-headed ruler.