 The authenticity of Philo's description of a cardan suspension has been doubted by some authors on the ground that the part of Philo's "Pneumatica" which describes the use of the gimbal survived only in an Arabic translation of the early 9th century.Thus, as late as 1965, the sinologist Joseph Needham suspected Arab interpolation.However, Carra de Vaux, author of the French translation which still provides the basis for modern scholars, regards the Pneumatics as essentially genuine.