Note 127 — XXVI. An Account of the Case of the late Right Honourable Horace Lord Walpole; being a Sequel to his own Account published in the Philosophical Transactions, Vol. xlvii. p. 43. and 472.
Reading edition
The two stones found in Lord Walpole's bladder were of this size, and weighed one of them 22 and the other 21 grains.