once took a
beautiful picture---at least, I thought it was beautiful---of a
flock of sheep, and when I tried to develop the plate in a hurry
I got one end light-struck, so it was no good."

"Yes, and once, when I was in a hurry to develop a roll of films I
had of a military parade," said Snap, "I got the hypo in the tank
instead of the developing solution, and that was the end of that
roll."

"This is a good rule to remember," said the photographer. "Never
open the shutter of your camera until you are certain you are ready
to take the picture, and never attempt to develop a plate or a film
until you are sure your chemicals are properly mixed, and until you
are sure you have everything at hand with which to work, and until
you are sure the plate or film is properly protected from the light."

The boys were surprised when Mr. Jally announced that it was supper
time and that he must go home.

"Gracious! And I told my aunt we'd be to supper by six o'clock!"
exclaimed Shep. "We'll have to leg it to her house."

"Come again to-morrow at nine o'clock," said the photographer, and
this the chums promised to do.

"Well, I've learned a whole lot to-day," said Snap as they walked
along. "I am sure I can take a much better picture than formerly."

"And I've learned one little lesson," came from Whopper. "After
this I am not going to take so many snapshots of landscapes. I am
going to take time exposures, and put my camera on a tripod, and
study the scene through the ground glass, to get the best view
possible."

Mrs. Carson, the doctor's sister, had given the boys their dinner,
and now she had supper on the table waiting for them. Their
experiments of the afternoon had made them hungry, and all
"pitched in" with a vigor that made the good woman smile.

"What do you intend to do this evening?" she asked.

"We are going to the circus, Aunt Jennie," answered Shep. "Father
said we might go."

"I thought as much. Don't stay out too late."

"We'll come home as soon as the show is over."

"Well, if it gets too late I'll put the key out for you---under the
front-door mat," said Mrs. Carson. "I fancy you can find your way
to your rooms."

"Certainly," answered Snap.

"You needn't stay up for us, Aunt Jennie," said Shep, who knew his
relative was in the habit of retiring early.

"I am not going to bed so very early, Shep. I am afraid some of
those tramps who follow the circus will come and rob me. I heard
th