I went to Greenwich, where his Majesty was trying divers grenadoes shot out of cannon at the Castlehill, from the house in the park; they broke not till they hit the mark, the forged ones broke not at all, but the cast ones very well. The inventor was a German there present. At the same time, a ring was shown to the King, pretended to be a projection of mercury, and malleable, and said by the gentlemen to be fixed by the juice of a plant.