1827 – UK
‘Tiny solid particles suspended in a fluid are in continuous random motion’
This motion is caused by constant collisions between the suspended particles and the fluid molecules.
In 1905 EINSTEIN studied Brownian motion and used it to calculate the approximate mass and size of atoms and molecules.
Brown is also remembered for discovering a small body within cells, which he named the nucleus (from the Latin for ‘little nut’). Plant cells were discovered by HOOKE.