Measurement of the Height of a Tower

This engraving depicts a cylindrical tower with an arched entrance on the right and a mathematical surveying instrument mounted on a tripod stool to the left. A dashed line connects the sighting apparatus on the instrument to the top of the tower, illustrating a line of sight. Below the horizontal arm of the instrument, the letters 'c' and 'd' serve as labels for the mathematical calculation.

This illustration originates from Robert Fludd's 'Utriusque Cosmi Maioris scilicet et Minoris metaphysica, physica, atque technica historia' (1617–1624), a foundational work of Renaissance natural philosophy and Hermeticism. It demonstrates the application of geometry to surveying, reflecting the era's fusion of mystical cosmology with empirical mathematical inquiry.