I wrote: >In terms of efficacy (lumens per watt), HOs and VHOs are as bad as >incandescents, which include metal halides. That's wrong as David Webb kindly pointed out to me. Metal halides are high-intensity discharge lamps and don't burn filaments to produce heat. Too many lamps ... too much confusion. Greg. Tong San Francisco, CA, USA gtong at sirius_com "Every infinity is composed of only two halves."