Compulsive habits usually refer to strange behaviour repeated by a person without a clear reason. For example, a kid may jump over a fence, instead of taking the normal passageway. Usually, children express compulsive behaviour as they are mischievous by nature.
(i) As per the story, Maxwell expresses compulsive habits such as the rituals of children who, on their way to and from school, must place their feet squarely on the centre of each paving block; must touch every seventh upright of the iron railings, or pass to the outside of every second lamp post.
(ii) Similarly, even Mijbil, while on his way home, would jump over the boundary wall railing and gallop the full length of its thirty yards, to the hopeless distraction both of pupils and staff within.