For more than a week before Hal's return from school the others had been busy getting the ammunition ready; they had dug up a quantity of sand from the bed of the stream, which, when mixed with a little clay and moistened with water, represented cannon-balls.  As, however, they had no cannon, these balls had to be thrown by hand; and as they scattered when they struck, they appeared more formidable than they really were.  But still one had been known to bring down the flag, and so win the day for the besiegers.