If the series for the perturbation term Ω contains a term of the form cos (v) ,integration yields terms such as v sin (v) which represent unbounded behaviour of the orbit. Clairaut adjusts the expansion to eliminate this effect. Firstly in this process, there is the technique of integrating while keeping slowly varying quantities such as c fixed and secondly there is a procedure to avoid secular terms which is related to the modern approach. Lagrange and Laplace developed and used this technique of obtaining approximate. The treatment in Laplace’s Trait´e de M´ecanique C´eleste [1] is very technical. In Laplace’s study of the Sun–Jupiter–Saturn configuration one can find the ingredients of the method of averaging and also higher-order perturbation. Lagrange, after discussing the formulation of motion in dynamics, argues that to analyze the influence of perturbations one has to use a method which we now call ‘variation of parameters’. Lagrange starts by transforming the problem to the standard form
如果扰动项Ω系列包含一个长期的形式COS（V），集成产量方面如V sin（V）代表的轨道无限的行为。克莱罗调整膨胀消除这种影响。在这一过程中，有整合技术的同时保持缓慢变化的量，如C固定，其次是一个过程，避免世俗的条款，是对现代的方法有关的。拉格朗日和拉普拉斯并以此获取近似技术。在拉普拉斯特征´e de M´ecanique C´eleste [ 1 ]的治疗是非常技术。在拉普拉斯的太阳–木星–土星一配置研究可以发现，平均的方法的成分和高阶摄动。拉格朗日，在讨论运动动力学公式，认为对扰动的影响已经使用一个方法，我们称之为参数的变化。拉格朗日开始通过将问题转化为标准形式
