[SOURCE: The Mark Twain Papers: Mark Twain's Letters, Volume 2: 1867-1868, ed. Harriet Elinor Smith and Richard Bucci (Berkeley: University of California Press, 1990).]
[Virginia City, May 1, 1868.
To Mary Fairbanks.

[From Mark Twain's Letters 2: 212]

My Dear Mother--
    . . . I lectured here--a little over sixteen hundred dollars in the house--gold & silver. The seats were all taken & paid for long before night, & then I stopped the sale of tickets, which made a large number of people mad--people who came at 7 P.M. & had to go away again. But I couldn't help that. I didn't want them standing up & bothering me. It was a miserably poor lecture. I shall write a better one the next time I come to San Francisco.

[San Francisco, July 5 1868.
To Mary Fairbanks.

[From Mark Twain's Letters 2: 234]

Dear Mother--
    I lectured on Venice night before last--large audience & fashionable--& gave so much satisfaction that I feel some inches taller, now. Mind, I do not forget that I am right among personal friends, here, & that a lecture which they would pronounce very fine, would be entirely likely to prove a shameful failure before an unbiased audience such as I would find in an eastern city or on board the Quaker City. I only claim that these citizens here call this a good lecture--I do not claim, myself, that it is. I am satisfied it would be pretty roughly criticised in an eastern town.
    But one thing I know--there is no slang, & no inelegancies in it--& I never swore once, never once was guilty of profanity.