Final answer:
John Paton had to travel at night for safety and to avoid potential dangers while trying to reunite with his family, as the desolation and silence hinted that the night offered protection.
Step-by-step explanation:
In Cannibals at Work, John Paton had to travel at night primarily for reasons of safety. The passage describes his journey as fatiguing and lonely, with an emphasis on the desolation of the area.
The silence and lack of human presence, accentuated by no barking dogs or signs of human habitation, suggest that it was safer to move under the cover of darkness to avoid potential dangers, such as hostile encounters with natives or wild animals.
His strong motivation to reunite with his family propelled him to press on despite his exhaustion and hunger. Additionally, the lack of details specifying direct threats during his night travel in the text likely means that the night offered some form of protection or concealment when traversing potentially hazardous territories.