Dear Sir James Ross

I fear you will think me very ungrateful & capricious, but such is not the case, when I say that I fear I must decline your kind invitation for tomorrow. The temptation made me break through my rule of dining by myself, but since you asked me, I have not been well, & I am in truth afraid of being knocked up if I dine out anywhere out of my own rooms.—

I let you know today that you may fill up my place more worthily.— With much regret & my sincere thanks.

Pray believe me | Yours truly obliged | Charles Darwin