From Mary Somerville   [23 October 1830]

My dear Sir

I send you a method of estimating the variations in the elements of the orbits during the periods of the perturbations in longitude and distance which will supersede the integration by parts of the same quantities depending on the second powers of the excentricities[sic] and inclination. I have applied this method to the great inequalities in the mean motions of Jupiter and Saturn in the end of the M.M.S. where this may come in if you approve.

I beg you will give my love to Mrs Herschel who I trust is perfectly recovered. I hope you have also had good accounts of her brother. Believe me

ever sincerely yours

Mary Somerville

Chelsea 23d October