A thief hides a precious jewel by placing it on the bottom of a public swimming pool. He places a circular raft on the surface of the water directly above and centeredover the jewel as shown in figure P35.55. The surface of the water is calm. The raft, of diameter $d=4.54 \mathrm{m}$ , prevents the jewel from being seen by any observer above the water, either on the raft or on the side of the pool. What is the maximum depth $h$ of the pool for the jewel to remain unseen?