“No; but we are going to get one,” answered Shep.

“They are quite valuable; but even with a card one must often use his own judgment as to just what stop to use and how much time.  If you are particularly anxious about a picture you had better take two or three exposures of it, instead of only one.  Even the best of photographers occasionally fail to get good results on a first trial.”

After that Mr. Jally brought forth several cameras he had used in outdoor work and explained how they might be used to the best advantage in taking different kinds of pictures and under various conditions.

“Strange as it may seem,” he said, “no two scenes can be handled alike.  In one the background may be very light and in the other very dark.  One day the atmosphere may be very clear, the next it may be very dense.”

“Yes, we know that, and we have found out that clouds over the sun make a big difference,” said Snap.

The boys spent the balance of the morning and nearly all of the afternoon with the photographer, and learned many things of which they had been formerly ignorant.  He recommended that they purchase and study several books on photography, and this they agreed to do.

“I see by the letter that Dr. Reed wishes me to pick out your cameras,” said Mr. Jally.  “I am going to the city Saturday and will get them and leave them at the doctor’s house Saturday evening.”

“And will you get the films and plates and other things, too?” questioned Whopper.

“Yes.  The doctor wants a complete outfit, including a daylight developing tank, and all the chemicals for developing and printing.  Then you can see what your pictures look like before you leave camp, and if a picture doesn’t suit you can take it over again.”

“Not if it’s a wild beast,” answered Giant with a grin.

“In the case of wild animals you had better save your films or plates until you get home.  Developing in camp is not conducive to the best work, and you might lose the very film or plate you wanted the most.”

“Yes, I know something about that,” said Whopper.  “I 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.”