The largest of the three, and perhaps the finest, was the one they first came to, which already was beginning to be called the cave of Robin Lyth. The dome is very high, and sheds down light when the gleam of the sea strikes inward. From the gloomy mouth of it, as far as they could venture, the lapping of the wavelets could be heard all round it, without a boat, or even a balk of wood to break it. Then they tried echo, whose clear answer hesitates where any soft material is; but the shout rang only of hard rock and glassy water. To make assurance doubly sure, they lit a blue-light, and sent it floating through the depths, while they held their position with two boat-hooks and a fender. The cavern was lit up with a very fine effect, but not a soul inside of it to animate the scene. And to tell the truth, the bold invaders were by no means grieved at this; for if there had been smugglers there, it would have been hard to tackle them. Hauling off safely, which was worse than running in, they pulled across the narrow cove, and rounding the little headland, examined the Church Cave and the Dovecote likewise, and with a like result. Then heartily tired, and well content with having done all that man could do, they set sail again in the dusk of the night, and forged their way against a strong ebb-tide toward the softer waters of Bridlington, and the warmer comfort of their humble homes. CHAPTER XVII DELICATE INQUIRIES A genuine summer day pays a visit nearly once in the season to Flamborough; and when it does come, it has a wonderful effect. Often the sun shines brightly there, and often the air broods hot with thunder; but the sun owes his brightness to sweep of the wind, which sweeps away his warmth as well; while, on the other hand, the thunder-clouds, like heavy smoke capping the headland, may oppress the air with heat, but are not of sweet summer's beauty.