Day offered to build a brick wall on between his lot and his neighbor's, and he did indeed build the way.
Assume: (1) Day built the wall in the expectation that Caton, his neighbor, would pay for half of it; (2) Caton had reason to know that Day had this expectation; (3) allowed him to build without voicing any objection; (4) then used the wall himself to his own benefit.
Under ยง 69(1), Caton
accepted Day's offer to build the way in return for Caton's paying for half of it.
did not accept Day's offer to build the way in return for Caton's paying for half of it.