1. F. Shu is at the Astronomy Department, University of California, Berkeley, CA 94720–3411, USA, and the Institute of Astronomy and Astrophysics, Academia Sinica, Taipei 115, Taiwan. H. Shang is in the Astronomy Department, University of California, Berkeley, CA 94720–3411, USA. A. E. Glassgold is in the Physics Department, New York University, New York, NY 10003, USA. T. Lee is at the Institute of Earth Science and the Institute of Astronomy and Astrophysics, Academia Sinica, Taipei 115, Taiwan.