Mrs. Gentrie said soothingly, “Isn’t there a clue in the fact that the second two letters are c-a, Rebecca? Not many letters would go with c-a. You have some of the vowels which would hardly fit. Then in the consonants, I would say that s is about the only one that would go with c. That gives you s-c-a.”

“Oh, I have it,” Rebecca said. “S-c-a-r-p... but whoever heard of a young salmon being called a parr?”

“You might look it up.”

Rebecca turned the pages of the dictionary. “Yes. Here it is. P-a-r-r.”

She worked quickly with her pencil, then looked at the watch again. For a moment there was silence, then she threw down the pencil. “I don’t know what good it does a body to try and concentrate when you keep thinking about empty tins being found on the shelves. Why would an empty tin be put on a shelf, anyway?”

Mrs. Gentrie smiled indulgently. “I’m sure I can’t tell you. Go back to your puzzle, Rebecca. I’m certain you’ll have much better than average intelligence. What else are you having trouble with?”

“A four-letter word meaning ‘an East Indian tree used for masts.’ ”

“Do you have any of the letters?”

“Yes. I’ve got the first two letters. — P-o.”

“What other words would give you a clue?”