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    PR # 32261                                                                   
     We propose to begin the systematic study of the spectra of high             
     redshift clusters of galaxies.  Specifically, we will make the first        
     determination of the cluster temperature function at a redshift other       
     than zero.  This measurement will discriminate among various models         
     of the evolution of the X-ray gas in clusters and will also determine       
     the mass density fluctuation spectrum on cluster scales.  This              
     proposal requests observations of the last six clusters in our              
     complete sample.                                                            
                                                                                 
                                                                                 
                                                                                 
                                                                                 
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