Suppose three thermal bodies with thermal masses, m1 , m 2 , and m 3 , are connected to each other in series and to two walls kept at T=0 with thermal conductors of equal thermal conductance, k1 , k 12 , k 23 , and k 3 . Suppose: i) the heat flowing across each conductor is equal to the temperature difference times the conductance and ii) the time derivative of the temperature in each thermal mass is the heat entering the body divided by its thermal mass