In June of 1962, Henri Marceau approached George L. Stout, Director of the Isabella Stewart Gardner Museum, with his concerns about the humidity levels in the Johnson galleries and its adverse effect on the condition of the collection. Stout, who had recently updated the climate control system at his museum, agreed to survey the galleries. His subsequent risk assessment, submitted to the Pennsylvania Company in August of that year, helped to direct the overhaul of the humidification system in the galleries.

This subseries also includes correspondence and specifications from Robert J. Sigel, Inc., consulting engineers for the climate control project, and various material about lighting and security systems.