In the last sentence in the first paragraph, the second word obviously should be "brick", and a "hypocaust" is a hollow space under the floor of an ancient Roman building, into which hot air was sent for heating a room or bath.
In the last sentence in the first paragraph, the second word obviously should be "brick", and a "hypocaust" is a hollow space under the floor of an ancient Roman building, into which hot air was sent for heating a room or bath.