The "dadim" were the faucets of the laver. During the era of the Mishkan, the laver had two faucets. During the period of the Second Temple, a priest by the name Ben Katin donated a laver with twelve faucets. This enabled all twelve priests who were chosen during the second lottery to bring the Tamid * offering of dawn to sanctify their hands and feet simutaniously.  The Area between the Ulam and the Mizbeach: The Parts of the Laver: The Pedestal
Contents:   Part I,    Part II,    Part III,    Part IV,    Part V,    Part VI,    Part VII