Clause # 17 The parties hereto being cognizant that the United States is at war and that a war emergency exists and that demands have been made by the United States Government unon the City and its facilities, and that other demands may in. the future be made, it is therefore understood and egreed between the parties hereto that in the event the United States Government, or any department er agency thereof, desires to lease or use any part of the Municipal Auditorium Building involved or affected by this lease, then this lease may be immediately cancelled by the lessor without notice thereof; and furthermore the lessor : also reserves the right to change the dates herein specified at lessor's dis- cretion, and the lessee hereby waives any claim he may have or which might arise by reason of such cancellation or change of dates.