Two types of near-blindness, one caused by cataracts and the other by opacity of the cornea, are operable if the retina has retained functionality.
In 1830, it took about 250 to 300 labour hours to produce 100 bushels (5 acres) of wheat. In 1975, it took just 3¾ hours.
Brewers began adding hops to beer in the 9th century AD. Today, nearly all beer is brewed with hops, which adds a zesty, bitter flavor to beer and acts as a preservative.
Breathing toner particles from photocopiers and printers is as bad for the lungs as smoking and can irritate eyes, nose, and lungs.
The modal age of retirement for teachers is about 59 years old.