Tom Swift and His Chest of Secrets by Victor Appleton

NED NEWTON was rather puzzled over Tom's long absence from the office. The day had passed and the young inventor had been at his usual desk for only a brief period in the morning. He had told Ned he was going into the little testing room and would soon be back.

Ned knew that Tom did not like to be disturbed when conducting experiments and tests in this "cubby-hole," as it was called, for it was made small purposely to avoid air drafts and vibrations. So when noon came and Tom did not appear for dinner, nothing much was thought of it, as he frequently missed a meal.