His work was both of a military and of a scientific nature, often combining these two aspects in his work on hydrography and cartography, drawing up charts of the Azores and the Canary Islands.
Kanyang trabaho ay pareho ng isang militar at ng isang pang-agham ng kalikasan, madalas Kombinasyon ng mga dalawang aspeto sa kanyang trabaho sa hydrography at kartograpya, drowing up ng mga tsart ng Azores at ang Canary Islands.