Manual Machines
These machines usually comprise an outer bowl and a smaller inner bowl with a hand-cranked mechanism which turns a paddle, sometimes called a dasher, to stir the mixture. The outer bowl is filled with a freezing mixture of salt and ice: the addition of salt to the ice causes freezing-point depression; as the salt melts the ice, its heat of fusion allows it to absorb heat from the ice cream mixture, freezing the ice cream.
This type of ice cream maker is inexpensive, but inconvenient and messy as the ice and salt mixture produces a lot of salty water as it melts, which the user must dispose of, and the ice and salt mixture has to be replenished to make a new batch of ice cream.
Some small manual units comprise a bowl with a capacity of about one pint (500ml) whose hollow walls are filled with a coolant. The paddle is often built into a plastic top. The mixture is poured into the frozen bowl and placed in a freezer. The paddles then are turned by hand every ten minutes or so for a few hours until the desired consistency and flavor is reached. Nancy Johnson invented the first hand-cranked model in 1843. She then sold the patent to William Young, who marketed the machine as the Johnson Patent Ice-Cream maker.
Read more about this topic: Ice Cream Maker
Famous quotes containing the words manual and/or machines:
“If the accumulated wealth of the past generations is thus tainted,—no matter how much of it is offered to us,—we must begin to consider if it were not the nobler part to renounce it, and to put ourselves in primary relations with the soil and nature, and abstaining from whatever is dishonest and unclean, to take each of us bravely his part, with his own hands, in the manual labor of the world.”
—Ralph Waldo Emerson (1803–1882)
“The machines that are first invented to perform any particular movement are always the most complex, and succeeding artists generally discover that, with fewer wheels, with fewer principles of motion, than had originally been employed, the same effects may be more easily produced. The first systems, in the same manner, are always the most complex.”
—Adam Smith (1723–1790)