c) applying said open face of said detector casing to said honeycomb structure at the end of the cells thereof remote from said support whereby air supplied to said first compartment is able to flow into {HEAD ~ at least those cells} of {TAIL ~ said honeycomb structure} which are covered at least partly by said first compartment 
of
c ) applying said open face of said detector casing to said honeycomb structure at the end of the cells thereof remote from said support whereby air supplied to said first compartment is able to flow into { HEAD ~ at least those cells } of { TAIL ~ said honeycomb structure } which are covered at least partly by said first compartment
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