Charlie, a 7-month-old boxer, may have had the best seat along West Cary Street yesterday. At the least, it was the wettest. The young yet stocky pooch immersed herself in a small, round swimming pool filled with water during the 26th Carytown Watermelon Festival. She was doing her best to stay cool from the oppressive heat that beat down on the estimated 100,000 people who traversed a six-block stretch during one of the hottest days of the year. Temperatures reached a high of 97 degrees, with the heat index even higher.