French and United Kingdom workers have published reports describing a sudden change in the secular acceleration, called an impulse or a jerk, which took place in 1969. They claim that this change took place in a period of a year or two and that the sources for the alleged jerk are internal. This paper questions their method or analysis, pointing out that their method of piecemeal fitting of parabolas to the data will always create a discontinuity in the secular acceleration where the parabolas join and that the place where the parabolas join is an a priori assumption and not a result of the analysis. It is also shown that the jerk defined as an approximation to the third time derivative is mostly of external origin. A short review of the uses of the terms impulses and jerks is given in the introduction.