Marcus Childermass, a professor of literature, named his four sons for characters in the novels of Tobias Smollett [The Chessmen of Doom; 6].
Bellairs never writes about Ferdinand Count Fathom Childermass, who is all but presumed deceased from Roderick's comments in Chessmen. Professor Childermass does attend one of his brother's funerals in Springfield, Massachusetts [The Mummy, the Will and the Crypt; 101], though whose service this is never is revealed.
Bellairs was most likely introduced to the works of Tobias Smollett during his post-graduate courses at the University of Chicago - though, knowing what we've learned about John's reading habits, Smollett could have been on his radar far earlier than that. The Adventures of Ferdinand, Count Fathom (1753) was Smollett's third novel and seems to be regarded as his least popular and respected.
Described as “the first novel by a major English writer...devoted to a thoroughgoing portrait of villainy”, the story tells the adventures of the title character’s treks across England and Europe. Filled with striking satiric thrusts at the legal, medical, and military establishments of mid-eighteenth-century Europe, the novel reveals Smollett’s capacities as a commentator on contemporary life. As one reviewers notes, “whistling as he makes love to your daughter so as not to let on that he is picking the lock on your safe with a toothpick between his toes definitely displays a sense of arrogance that one must admire!”