# Maximilien Toepler

$R(t)={\frac{k_T D} {\int_{0}^{t} I(t) \, dt}}$
where I(t) is the current in the arc discharge at time t, and D is the gap between the electrodes. The parameter $k_T$ is a constant whose value is $4 \times 10^{-3} \, V \cdot s^{-1} \cdot m^{-1}$.