Chapter 2: Page 12: Line 5 (78)

 In this, as in all else,—
Y'r obd't s'v't.
Jeremiah Dixon.—

* * * * * * * * * *

Line 78 Vulgarized:
Sincerely yours,
Jeremiah Dixon

Subtext:
There isn't any subtext. This is how everybody signed letters in the 1700s. Everybody was suddenly everybody else's eager servant. And they acted like vowels were a rare commodity not to be wasted. But I guess apostrophes were as plentiful as Passenger Pigeons.