Message transmission plants

Claim 1

AN INSTALLATION, FOR THE TRANSMISSION OF MAIL, OR THE LIKE, IN CARRIERS PROPELLED THROUGH PNEUMATIC TUBES, COMPRISING A TRUNK TUBE LINE CONNECTED TO AT LEAST ONE AIR PUMP HAVING PUMP VALVES CONTROLLING THE DIRECTION OF FLOW, CARRIERS FOR HOLDING MAIL AND MOVING THROUGH SAID LINE, A PLURALITY OF BRANCH TUBE LINES EACH HAVING AT LEAST ONE MESSAGE STATION CAPABLE OF SERVING EITHER AS A DISPATCHING STATION OR AS A DESTINATION STATION, EACH SAID BRANCH TUBE LINE BEING CONNECTED TO SAID TRUNK LINE BY A DIVERTER HAVING SEVERAL ADJOINING OUTLETS AND EMPLOYING INTERNAL SWITCHING MEMBERS FOR DIRECTING THE CARRIER PROPELLING AIR FLOW FROM SAID AIR PUMP NORMALLY PASSING ONLY THROUGH THE TRUNK LINE INTO A SELECTED ONE OF SAID SEVERAL OUTLETS, A PLURALITY OF FIRST ACTUATING DEVICES LOCATED IN SAID TRUNK LINE NEAR EACH OF SAID DIVERTERS FOR CAUSING A CARRIER-OPERATED SIGNAL, A PLURALITY OF SECOND ACTUATING DEVICES LOCATED IN OR NEAR THE MOUTH OF EACH OF SAID MESSAGE STATIONS FOR CAUSING A CARRIER-OPERATED SIGNAL, AN ELECTRICAL CONTROL SYSTEM INCLUDING SIGNALLING MEANS FOR MARKING OUT A DESIRED MESSAGE STATION AS THE DESTINATION STATION AND ALSO RESPONSIVE TO CARRIER-ACTUATED, CARRIER POSITION INDICATING SIGNALS ARISING FROM A CARRIER UPON ENGAGEMENT WITH ONE OF SAID FIRST ACTUATING DEVICES TO CONTROL THE SAID PUMP VALVES AND THE DIVERTERS AS TO CONVEY A MAIL CARRIER FROM ANY STATION OF THE INSTALLATION TO ANY OTHER STATION, SAID ELECTRICAL CONTROL SYSTEM BEING