Note 1: (espalier)
The American Heritage Dictionary defines espalier as:
Note 2: (Will Mr. Frank Churchill pass through Bath as well as Oxford?)
Harriet's geography seems more than a little faulty, either because all things in her life revolve around Mr. Elton, or perhaps because Mrs. Goddard's school did not do much teaching.
To pass through Bath on a route between Oxford and Surrey, one would have to take a detour of about 100 miles. Here is a map of southern Britain to show the relative positions of Oxford, Bath, and Surrey: