What reminder does Higgins receive when the church clock strikes? What does he do in response? (Act 1)

The ringing of the clock reminds Higgins of Christian charity, after which he throws money into Eliza's basket.

The church clock strikes the second quarter.

HIGGINS [hearing in it the voice of God, rebuking him for his Pharisaic want of charity to the poor girl] A reminder. [He raises his hat solemnly; then throws a handful of money into the basket and follows Pickering].