static void Main() { // Create a speedometer... Speedometer speedo = new Speedometer(); // Create a monitor... SpeedMonitor monitor = new SpeedMonitor(speedo); // Add automatic gearbox as an observer AutomaticGearbox auto = new AutomaticGearbox(speedo); // Drive at different speeds... speedo.CurrentSpeed = 50; speedo.CurrentSpeed = 70; speedo.CurrentSpeed = 40; speedo.CurrentSpeed = 100; speedo.CurrentSpeed = 69; Console.Read(); }