Balloon rally in chalk

This chalkboard drawing is located in WH14NW, and the only identifying mark is "JM 78". While the formulas and diagrams around this drawing change regularly, this beautiful picture of a balloon rally has remained untouched for over 40 years! Drawing: JM. Photo: Jamieson Olsen

This chalkboard drawing is located in WH14NW, and the only identifying mark is “JM 78”. While the formulas and diagrams around this drawing change regularly, this beautiful picture of a balloon rally has remained untouched for over 40 years! Drawing: JM. Photo: Jamieson Olsen