of Mathematics and Vice-Rector of the Roman College until 1633, when the Order transferred him to the Jesuit college in his home territory of Genoa. There he served not in a teaching capacity but as confessor, but although he no longer held a senior academic post, he continued to review and advise on a number of the Order's scientific projects. The Republic of Genoa also consulted him on naval engineering, including one for an 'unsinkable' ship. After a second period in Rome he served once again as confessor at the college in Genoa, and then as vice-rector, between 1651-1653. Architectural projects Grassi was involved in advising on a number of building projects for the Jesuit order. His interest in architecture appears to date from 1616 when he began teaching mathematics, and at the same time assumed the title (building consultant), for all the construction projects of the Jesuit order. He appears to have fulfilled thus responsibility sporadically between 1616 and 1628. After this he devoted a great deal of his time to architecture, although many of his schemes were destined never to be built. Among these was his first known design dating from 1620 and 1621 at the church of S. Ignazio near the Jesuit college of Ajaccio. In 1624 he made a trip to Sezze to check on progress in construction of the local college and the church of Ss. Pietro e Paolo, begun in 1601 to a design by father Giovanni De Rosis. Grassi made a number of alterations and additions to this project. In 1626 the rector of the college in Siena, invited him to take charge of the transformation of the church of San Vigilio. It was his only completely realised design, and it was a major influence on Jesuit architecture, combining excellent functional use of space with sober decoration. At the end of 1626 he was called to Rome to help with the building works on the church of Sant'Ignazio and in 1627 he was made prefect of its construction. In 1632 he was called to Terni to assist with the building of the church of S. Lucia; and soon after, with the college of Montepulciano and a church in Viterbo. His architectural work was reduced after his move to Genoa in 1633, but in 1634 he began to work on the project for a new Jesuit college in the city, which was the cause