Who invented the milk jigger and in what year?

The milk jigger was invented in the 1930s by Ernest "Ernie" Schmidt, a bartender at the Stork Club in New York City. Schmidt invented the jigger to measure the correct amount of milk for a Jack Rose cocktail, which was made with applejack brandy, grenadine, and lime juice. The milk jigger is a small glass or metal container with a spout, typically made with two different capacities, one for a half-ounce and the other for one ounce. The jigger is used to measure and pour liquids in bartending and is essential for making cocktails with precise measurements.