One of the 14th-century Oxford Calculators, William Heytesbury, lacking differential calculus and the concept of limits, proposed to measure instantaneous speed "by the path that would be described by if... it were moved uniformly at the same degree of speed with which it is moved in that given instant".
Un dos calculistas de Oxford do século XIV, William Heytesbury, carecendo do cálculo diferencial e o concepto de límites, propuxo a medida da velocidade instantánea "do xeito que sería descrito por se... se movese uniformemente no mesmo grao de velocidade co cal se move naquel instante".