| Physics & Mechanics | physics-and-mechanics | 2,539 | Weights, forces, motion, levers, friction, percussion, equilibrium, falling bodies, statics and dynamics, perpetual-motion studies. The abstract science of force and motion, as distinct from a built machine (machines-and-devices). |
| Hydraulics | hydraulics | 977 | Water and its movement: rivers, canals, vortices, waves, currents, the erosion and deposition of water, mills and water-lifting understood as the science of water. A water-lifting device itself may also carry machines-and-devices. |
| Anatomy | anatomy | 104 | The internal structure of the human or animal body: muscles, bones, skeleton, organs, heart, cranium, vessels, nerves, dissection, the embryo and womb. NOT the outward figure or proportion (use figure-studies). |
| Geology | geology | 151 | Rock, mountains, strata, fossils, erosion, sediment, the body of the earth and its changes over time. |
| Astronomy | astronomy | 144 | The moon, sun, stars, planets, the cosmos, eclipses, the firmament; Leonardo’s account of the pale light of the moon. |
| Optics & Light | optics-and-light | 1,008 | Light and shadow as physical phenomena: reflection, refraction, rays, mirrors, the eye and the mechanism of vision. The theory of shading FOR pictures overlaps painting-and-perspective; tag both when both apply. |
| Botany | botany | 184 | Plants and their growth: trees, leaves, flowers, seeds, germination, the branching and structure of vegetation. |
| Flight | flight | 299 | The flight of birds, wings, feathers, the behaviour of air and wind in flight, flying machines, the ornithopter and aerial screw, balance in the air. |
