Experiments on gravitation.

The theoretical setting of the experimental study of gravitation is indicated and a brief account is given of experiments on gravitation from Newton onwards. The main content of the review comprises surveys of three groups of experiment: the investigation of the inverse square law, studies of the weak equivalence principle and determinations of the constant of gravitation. Attention is called to the reasons for the difficulties of carrying out experiments on gravitation. In summary, it is concluded that there is no evidence for deviations from general relativity and that gravitation is mainly a manifestation of the geometry of spacetime.