In a nickel book marked “Compositions” Tim’s left hand added the entries. He had used the correct symbols—F x, F 2, F 3; Ss, Bl.

“The dominants in capitals,” he explained, “B for black, and S for short hair; the recessives in small letters—s for Siamese, 1 for long hair. Wonderful to write 11 or ss again, Peter! Twice more. And the other kitten is carrying the Siamese marking as a recessive.”

He closed the book in triumph.

“Now,” and he marched to the covered thing on the table, “my latest big secret.”

Tim lifted the cloth carefully and displayed a beautifully built doll house. No, a model house—Welles corrected himself swiftly. A beautiful model, and—yes, built to scale.

“The roof comes off. See, it has a big storage room and a room for a play room or a maid or something. Then I lift off the attic—”

“Good heavens!” cried Peter Welles. “Any little girl would give her soul for this!”

“I used fancy wrapping papers for the wallpapers. I wove the rugs on a little hand loom,” gloated Timothy. “The furniture’s just like real, isn’t it? Some I bought; that’s plastic. Some I made of construction paper and things. The curtains were the hardest; but I couldn’t ask grandmother to sew them—”

“Why not?” the amazed doctor managed to ask.

“She might recognize this afterwards,” said Tim, and he lifted off the upstairs floor.