It is March 7th, the first day of Spring break, and you have not made it quite to beach destination. Perhaps you could have, except for that sheriff with the radar trap—but that is behind you as you shower in your motel room not too far from your final destination. In the morning you and your seven friends will be off bright and early in your compact car and you’ll all be at the beach for a late afternoon swim and the beginning of a well-deserved Spring break—and so to bed. You are startlingly awakened shortly before midnight by a loud knocking on the door. Good grief! It’s the same sheriff you saw earlier in the day! “Sorry for what happened north of here today, folks, but I need your help. There has been a murder; my coroner has gone fishing, but I noticed a copy of your Heat & Mass Transfer book on the rear window deck of your vehicle and I have a thermometer. There are several suspects and your help is needed to tell me which one is the likely culprit,” It seems that the victim, one John Lurie, was known as a dealer in hot cars, and may have been ready to confess to the police the roles of his accomplices, Gus Fourier and Bill Gurney. John’s body was found on the beach, where the waves of the outgoing tide were gently washing over it.

Gus has an iron-tight alibi for the day of the murder—he was with a group of gambling friends from dinner (6 PM) until interviewed by the sheriff an hour ago. Bill was seen shopping with a girlfriend from early morning until 6 PM, and the sheriff has been unable to locate him since. You accompany the sheriff to the beach, where you determine that John Lurie’s centerline temperature is 86.5°F and the water temperature is 80°F. He looks as if he might be 5 ft, 8 or 9 in. tall and weigh 200 lb. Which of the two suspects should the sheriff apprehend?