Description: Papers of Vincent S. Day, '17 (1894-1992), research professor of mechanical engineering of the Engineering Experiment Station (1921-28), including photographs of the Holland Vehicular Tunnel ventilation test facility erected on campus and test equipment (1921-22); reports on research and experiments prepared as part of the investigation of warm air furnace heating which was conducted by the Engineering Experiment Station in cooperation with the National Warm Air Heating and Ventilation Association - NWAHAVA (1920-24); photographs of the furnace testing plant showing details of equipment and test experiments (1918-25); annual reports to NWAHAVA on warm air furnace research work (1922-27); reports on research and experiments conducted at the Warm Air Heating Research Residence which was erected in Urbana by NWAHAVA (1925-27); and photographs showing plans, construction, interior and exterior detail, heating equipment and dedication of the Research Residence and NWAHAVA trustees, advisory committee and publicity committee (1924-27).