To Mary Somerville   [31 March 1830]

Slough March 31/30

My dear Madam,

I have here so much of the latter part of your MS as I have read, and with the exception of one or two slight observations (which I have noted) I don’t think it can be materially improved. perhaps a little explanation of the object of the curious analytical proof by which the arbitrary constants are so beautifully [illegible] in the integrals of the General Equations of the Elliptic motions might be desirable (vis: to facilitate the expression of the variations of the Elements) — but perhaps you have reserved this for that part in which you treat expressly of this point. I shall think it no trouble to resume the subject when retouched & interpolated however as you prefer and, indeed, shall probably find greater facility in doing so and obtain a better general view by doing so than by at once returning the whole — which however I will take can you shall have next Thursday through the kindness of our good friend.

I am happy to be able to tell you that this morning Mrs H presented me with a daughter and is as well as can be reasonably wished for.

I am dear Madam

yours very truly

J F W Herschel