My dear Sir

It may appear ridiculous or not very credible, but in simple truth I am not equal to taking the chair of the Nat. Hist. Section, in Liverpool, where I hope to attend.² Very little fatigue, or excitement or anxiety (of which I sh^d. have plenty) almost invariably brings on so much swimming of the head, nausea, & other symptoms, that the effort of sitting 2 or 3 (or even less) in a public chair would be quite intolerable to me.—

I assure you I feel to the full the honour of being asked to act as President to a section of the Brit. Association; & for this honour & others, I am (as I believe) indebted to you.— If you have occasion to make any excuse for me to others, be so kind as to make a general one on the score of health.—

Pray believe me, | Yours sincerely & obliged | Charles Darwin Colonel Sabine | &c &c &c