As for the exact depth reached, it was very easy to ascertain that; the Professor measured accurately the angles of deviation and inclination on the road, but he kept the results to himself.
Quant à connaître exactement la profondeur atteinte, rien de plus facile. Le professeur mesurait exactement les angles de déviation et d'inclinaison de la route, mais il gardait pour lui le résultat de ses observations.