Upper and lower manually operated valves illustrated at 24 and 25, respectively, are illustrated for supplying {HEAD ~ air} through the lines 24a and 25a to {TAIL ~ the air jet devices} 
Upper and lower manually operated valves illustrated at 24 and 25 , respectively , are illustrated for supplying { HEAD ~ air } through the lines 24a and 25a to { TAIL ~ the air jet devices }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL