Why do we call a cooling unit Ton refrigeration, although Ton is a unit of mass ? ;)

Ton refrigeration is is a unit of power defined as the heat of fusion absorbed by melting1 short ton (2,000 lb;0.893 long tons;0.907 t) of pure ice at0 °C (32 °F) in24 hours.

It is equivalent to the consumption of one ton of ice per day and originated during the transition from stored natural ice to mechanical refrigeration.

A refrigeration ton is approximately equivalent to12,000 BTU/h or3.517 kW.

Source