The Whiskey mash
A mechanical metal stirring unit with a central bevel gear, installed to make stirring easier. That way the sugar could not only be extracted faster but also more efficiently. Less sugar was left in the husks of the grain, and the whisky became more affordable.
The mash has to be stirred for some time to extract the malt sugar from the grist. In earlier times, a lot of water used to evaporate during this process, and with the water steam the temperature fell constantly, which further impaired the extraction process. Only in the last century, when energy costs rose, nearly all mash tuns were equipped with a lid made of sheet metal (e.g. copper) in order to limit the loss of energy.