BIFOCALS
Benjamin Franklin invented many helpful things in society. One was bifocals which are eyeglasses with an upper and lower half, the upper for distance, and the lower for reading. He invented these for people like him who suffered a condition called presbyopia. Franklin wrote, in August 1784 to his friend George Whatley, that he was "happy in the invention of double spectacles, which serving for distant objects as well as near ones, make my eyes as useful to me as ever they were."
FRANKLIN STOVE
In colonial America, homes were warmed by a fireplace. Franklin invented the Franklin stove in 1742 which is a metal-lined fireplace that stands in the middle of a room. It has rear baffles for improved airflow. It provides more heat and less smoke than an open fireplace and uses less wood. This cast-iron furnace would radiate heat from the middle of the room in all directions, and the iron walls even absorbed heat, providing warmth to the room long after the fire went out.
GLASS HARMONICA
Benjamin worked with Charles James to create a musical instrument called the Armonica which had its world premiere in early 1762 played by Marianne Davies. Franklin's foot-treadle-operated instrument held 37 glass bowls. The musician touched the rims of the bowls with fingered moistened from the water trough. The bowl-rims were color-coded, according to the note.