ok the black box from under his arm. "What are you going to do
now, you funny fellow?"

"Take a picture of that ledge," said Billy, looking around for a flat
rock or a stump upon which to place his box.

"Wait a minute till we get back," said Blaisdell, who had joined Jack at
the gully. "It looks to me as if there was a cave down there. There is
some sort of an opening at the bottom of the ledge, seems to me."

"Yes, so there is. I never noticed it before. How are you going to get a
picture, Billy? That is no camera you have. Where is your lens?"

"Haven't any! I can take a picture without a lens, only it will require
more time to make the exposure."

"Take a photograph without a lens?" said Percival in a tone of doubt,
mixed with scorn. "You must be crazy!"

Several of the boys thought the same as Dick, and laughed heartily at
what they considered one of Billy's harum scarum schemes.

"Go ahead and laugh, boys," said the good-natured fellow, as he placed
his small square box on top of a flat rock he had found, and pointed it
toward the ledge at the foot of which Blaisdell had discovered his
supposed cave entrance. "I know something that you fellows do not, and I
am going to get a picture. The light is fine, for it just sifts nicely
through the trees, and the sun is quite high enough yet."

"Yes, but Billy, if you have no lens nor shutter, how are you going to
take a photograph?" asked Blaisdell. "That doesn't look like anything
but a square box."

"That is all it is, but it is a camera just the same. Did you never hear
tell of a pinhole camera, my boy?"

"No, I did not. What is it?"

"I have a plate in this box, and it is set at what they call a universal
focus. That is, I can take a picture of something not too close, and
one at a distance. The box is lined with black paper, and in front there
is a very small hole, now covered by a flap of the same stuff. This hole
will admit the light fast enough, and yet not too fast, and as my plate
is sensitized, I can get a picture even if I have no lens. Did you ever
see a 'camera obscura,' as they call them?"

"Oh, you mean one of those things that take a panoramic view of the
beach and everything in sight? People get shown up sometimes when they
don't know it."

"Yes, that's the thing. You don't get a real photograph there, but you
see everything shown up on a table, as the thing at the top revolves.
Well, I will get a picture with my pinhole camera even if I ha