compressive forces, can have holes in the webbs for evacuation, and can have radiator material inserted into the holes. The material is made by Hexcel Corp. All front and back walls could be of 5 mil stainless steel or less the steel will then have less radiation lengths than the hydrogen (.028 compared to.06). We have not done detailed designs of these cells. A3 -3, ! I I,t I,. We have primarily dwelt on the use of drift chambers over spark chambers for the following reasons: a) Spatial precision is potentially higher b) Track pair resolution is potentially higher c) Operation in a magnetic field is more straightforward. d) Continuous sensitivity gives lower dead times e) Sparks and hydrogen are uncomfortable if only psychologically. The debits of drift chambers rest on the unknowns of a new technique. Some of the detailed problems are brought out in Appendix