Describe Mr. Grover, Herriot's dentist in Darrowby and Hector McDarroch the dentist James went to as a child in Glasgow.

Mr. Grover is gentle and is careful not to instill fear in James. Hector McDarroch was was a big, good-natured man but used primitive dental equipment such as a foot-operated drill and didn't care how much pain he inflicted on his patient.