Note 4 — Chapter I

“I remember once,” says Dr. Stukely, “when I was deputy to Dr. Hailey, secretary at the Royal Society, Sir Isaac talked of these kind of instruments. That he observed the chief inconvenience in them was, that the hole through which the water is transmitted being necessarily very small, was subject to be furred up by impurities in the water, as those made with sand will wear bigger, which at length causes an inequality in time.”—Stukely’s Letter to Dr. Mead.—Turnor’s Collections, p. 177.