Summer tunic

These long-sleeved, woolen tunics are threaded with with tubes leading to a small phlogiston boiler that hangs from the belt of the wearer. The boiler runs heated water through the tubes to keep the wearer "as warm as a summer day" even in the coldest weather. The flow of water may be adjusted such that the wearer feels anywhere between 1 and 60 degrees warmer than the outside environment.