M&D spoiler, p. 19: Mathematical joke

[Penny Padgett]

Hi all,

Among the benefits of being married to an engineer:  he can parse
mathematical jokes.  I showed my husband the question that someone 
lobs at the Learned English Dog on p. 19:

  What is the Integral of One over (Book) d (Book)?

The answer, says he, is log (Book).  Mildly funny for a novel about
astronomers, and a worthy companion to the GR joke about log Cabin/
C = Houseboat.

Penny