Scientific equipment. Historical artwork of a range of equipment used for scientific measurements and drawings. At centre left is a hydrostatic balance. This is used to measure the mass of an object in water and in air, to enable a calculation of the object's specific gravity. At upper right are calipers, at top left is a set of vernier calipers, and between them is a sextant. At centre right is a protractor with a moveable arm to sight or mark angles. Below the hydrostatic balance are two more calipers. At lower left is a drafting compass and to its right a more complex instrument also used for geometric drawings.