by Luther Brefo
Here is some info and pictures on the Hancock 4700 (with the reflector as on LA&L 72) and 4710 (without the reflector).
http://trainhorns.net/other/hancock.html
http://atsf.railfan.net/airhorns/h4700.html
http://trainhorns.net/other/hancock.html
http://atsf.railfan.net/airhorns/h4700.html