Waistcoat
In his diary on June 1, 1772, George Washington described Virginia summers as "very hot & Sultry." To offset the extreme temperatures, gentlemen like Washington wore suits made of light weight and breathable white cotton. Washington would have likely worn this cotton waistcoat with matching breeches as he surveyed his farms in the morning, only to change into more formal day wear when he returned to the mansion to greet or entertain guests.
See also breeches, W-1515.