Abstract: An assembly for permitting temperature measurements at a large number of locations within a vessel, which assembly has a spreader-reducer for compacting a significantly large number of thermocouple cables into a relatively small volume so as to permit passage through one or more vessel nozzles. The thermocouple cables each has a heat expansion portion as well as a seat, thereby permitting a series of horizontal arrays of thermocouple junctions positioned at different depths within the vessel.