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    PR # 31224                                                                   
     We select two distant clusters of galaxies (z = 0.54,0.41) from the s       
     ample of Dressler & Gunn 1992. The cluster of this sample are all ric       
     h, concentrated ones like the nearby Coma Clusters. >From X-ray spect       
     roscopy of these objects, we investigate the relation between luminos       
     ity and temperature in distant rich clusters. At the same time we can       
      measure excess absorption. Using these investigation, we can study d       
     ynamical evolution of ,the most massive objects in the Universe, clus       
     ters of gas, galaxies and dark matter.                                      
                                                                                 
                                                                                 
                                                                                 
                                                                                 
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