Sentence:  As they have no hour glasses, they measure their time by a kind of clepsydra. It is a small brass basin, about four inches in diameter, made thin enough to float on the water, with a hole in the bottom which admits as much as to fill it exactly in one <WSD>gurry</WSD>, or twenty-two and a half minutes. 
Meaning of the word marked with <WSD> tags:  The time interval indicated by striking the gurry. Originally, this was twenty-two and a half minutes, but later, under British influence, changed to an hour.