It had usually been Paul's complaint that the boat was too far behind; but after the cow incident, it was just the other way.

They were always so far ahead that it was hard to keep them in sight.

The darkey was bribed to this unwonted exertion by presents of neckties and other fancy articles which the Doctor sacrificed from his wardrobe.
The latter had visions of that cow's owner in vengeful pursuit.
While paddling along one morning, the boat being quite a distance below him, Boyton heard a terrific fusillade from the gun.

He thought the Doctor was shooting away all the cartridges.

The boat was surrounded by smoke and Paul drove ahead to see what was going on.