In the author's paper “Drift” (Lighthill 1956) there are mistakes which need correction. Equation (28) should read $\phi \sim -\frac {m}{4\pi U_r}\;\; as \;\; r \rightarrow \infty$ (28) since the definition of the disturbance potential ϕ (p. 35) states that the full velocity potential is U(x + ϕ). Hence by (18) equation (29) for the asymptotic form of the secondary flow due to a source should read $v_x = -\frac {Amy} {4 \pi U (y^2 + z^2)} \left(1 + \frac{\chi}{r}\right),\;\;\;\; v_y = -\frac {Am}{4\pi Ur}, \;\;\;\; v_z=0$ (29) where as well as the U's a 4π was accidentally missing from the version printed and a y misprinted as x.