But this stupendous success gained Harrison only a small victory. The Watch and its maker still had lots of explaining to do. That autumn, the board offered to hand over half the reward money, on the condition that Harrison hand over to them all the sea clocks, plus a full disclosure of the magnificent clockwork inside H-4. If Harrison expected to receive the full amount of the £20,000 prize, then he would also have to supervise production of not one but two duplicate copies of H-4—as proof that its design and performance could be duplicated.

