Astronomer at work, 1551.
© Science Museum / Science & Society Picture Library
Illustration from 'Breve compendio de la sphera y de la arte de navegar' (1551) by Martin Cortes (1532-1589). The top illustration shows an astronomer with his instruments, pointing at the sun. Below is a coat of arms with a helmet, swords, and stylised leaves. The 'Breve compendio' ('Short compendium of the world and of the art of navigation') consists of three parts: the first twenty chapters deal with the composition of the world and the universal principles of the art of navigation; the second twenty chapters consider the movements of the sun and the moon and the effects they produce; and the final fourteen chapters deal with the construction and use of instruments and the rules of the art of navigation.