At the end of 1839 his eldest child was born, and it was then that he began his observations ultimately published in the 'Expression of the Emotions.' His book on this subject, and the short paper published in 'Mind,' (July 1877.) show how closely he observed his child. He seems to have been surprised at his own feelings for a young baby, for he wrote to Fox (July 1840): "He [i.e. the baby] is so charming that I cannot pretend to any modesty. I defy anybody to flatter us on our baby, for I defy any one to say anything in its praise of which we are not fully conscious...I had not the smallest conception there was so much in a five-month baby. You will perceive by this that I have a fine degree of paternal fervour." During these years he worked intermittently at 'Coral Reefs,' being constantly interrupted by ill health. Thus he speaks of "recommencing" the subject in February 1839, and again in the October of the same year, and once more in July 1841, "after more than thirteen months' interval." His other scientific work consisted of a contribution to the Geological Society ('Geol. Soc. Proc.' iii. 1842, and 'Geol. Soc. Trans.' vi), on the boulders and "till" of South America, as well as a few other minor papers on geological subjects. He also worked busily at the ornithological part of the Zoology of the "Beagle", i.e. the notice of the habits and ranges of the birds which were described by Gould.] CHARLES DARWIN TO C. LYELL. Wednesday morning [February 1840]. My dear Lyell, Many thanks for your kind note. I will send for the "Scotsman". Dr. Holland thinks he has found out what is the matter with me, and now hopes he shall be able to set me going again. Is it not mortifying, it is now nine weeks since I have done a whole day's work, and not more than four half days. But I won't grumble any more, though it is hard work to prevent doing so. Since receiving your note I have read over my chapter on Coral, and find I am prepared to stand by almost everything; it is much more cautiously and accurately written than I thought. I had set my heart upon having my volume completed before your new edition, but not, you may believe me, for you to notice anything new in it (for there is very little besides details), but you are the one man in Europe whose opinion of the general truth of a toughish argument I should be always most anxious to hear. My MS. is in such confusion, otherwise I am sure you should most willingly if it had been worth your while, have looked at any part you choose.... [In a letter to Fox (January 1841) he shows that his "Species work" was still occupying his mind:--