                                                       ͻ
   Alpabet                        Masonry              Pottery                              Bronze_Working                           Ceremonial_Burial              HorseBack_Riding      The_Wheel
                                                     ͼ                                                                                                                              
                                                                                                                                                                                            
                                       Ŀ                                                                                                              
                                                                                                                                                                                          
        Ŀ                           Ŀ                            Ŀ                                             
                                                                                                                                                                                     
   Code_of_Laws         MapMaking       Writing        Mathematics               Currency    Iron_Working                                    Mysticism                                       
                                                                                                                                                                                      
                                                                                                                                                                                      
                                                                                                                                         Ŀ                                        
                                                      ĳĳĳĳĳĿ                                             
                                                                                                                                                                            
     ĳĳĳĳĳĳĳĳĳĿ                                                              
                                                                                                                                                                               
         ĳĳĴ    ĳĳĳĳĴ                                                Astronomy                                         
                                                                                                             Monarchy                                                           
    Literacy                       Trade                                                                                 Ĵ                                             
                                                                      Construction                                                                                                
                           ĳĳĳĳĳĳĳĳĳĿ                                               
                                                   ĳĳĳĳĳĳĳĳĳĳ                                        
                                                                                                                               Navigation                                          
 ĳĿ                                  ĳĳĳ                                                             
             The_Republic                                                                     ĳĿ                                                 
                        ĳ                         Feudalism           ĳĳĳĳĳĿ 
        ĳĳĳĳ            ĳĳĳĳĳĿ                        
                                                                                                                          ĳĴ                                             
                                                      Ŀ                                             Physics                                           
          ĳĳĳĳ          ĳĳĳĳĳĴ                                             
                                                                                                                                                  ͻ                   
               ĳĳĳĴ                                                                                   Magnetism                       Chivalry               Engineering
                    ĳĳĳĿ                                                                                                         ͼ                    
  Philosophy               ĳĳĳĳĳĳĳĳĳ  
                                                                                                                                                                             
     ĳĳĿ  Invention                                                                                                                                                  
                                                                                                                                                                             
Democracy   Medicine           Banking                                                                                                                                             
                                                                                                                                                                                
                                ĳĳĳĳĳĳĳ                                                
Ĵ                ĳĳĿ                                                                                                                              
             ͻ                                           ĳĳĳĳ                                                            
  University   Religion                              ĳĳĳĳĴ                                                                                           
              ͼ           Ŀ                                                                                                                                           
                                                                                                                                                                                
                          Steam_Engine              Gunpowder                 Bridge_Building                                                                                             
                                                                                                                                         
                                                                                                                                         
               ĳĳ                                                                                              
                ĳĳĴ                                                                                     
             ĳĳĿ                                                                                                             
          ĳĳĳĳĳĳĿ                                                                                         
                                                                                                                                     
        Chemistry                            Metallurgy                                                                                  
                                                                                                                                       
                      ĳĳĳĳĳĳĳĳĳ                                      
   Ŀ                                    ĳĳĿ                                                                          
      ĳĳ             ĳĿ  ĳĳĳĳĳ                                                           
                        Ŀ                                                                                                      
Explosives      Theory_of_Gravity           RailRoad          Electrycity                                                                    
                                 ĳĳĳĿ                                                                                    
  Ŀ              ڳĿ                                                                                               
           ĳĿ  Ŀ        ĳĳĳĳڳ   ĳ
                                                                                         
     ͻ                                                                        
     Conscription          Atomic_Theory                   Electronics                       
     ͼ                                                                          
                                                           Ŀ                               
                                                                  Ŀ                       
  Ŀ                                                                              
                                                                                            
Ŀ                             Industrialization             Computers                        
                                                                                              
       ĳĳĳĳĿ         Ŀ                           
                             Ŀ                                             
  Communism             The_Corporation             Steel                                         
                                                                                               
                                      ĳ                                            
                                                Ŀ                                 
                                                                                               
                      Ŀ   Ŀ                                               
                                        ͻ                                   
                        Refining          Genetic_Enginiring                                   
                                         ͼ                                   
                                                                                         
                                                                         
            Combustion                                                                           
                                                                                                
                ĳĳĳĳĿ  ĳĳĳ
                                                                       
                                  Automobile            Flight             
     Ŀ                                                   
               ڳ                                           
                                                                         
                   Mass_Production                     Advanced_Flight   
                                                                           
                                                                           
               Ŀ                                 ĳĳ
Ŀ  ĳĳĿ                           
   ͻ      ͻ                                   
   Recycling      Labor_Union      Nuclear_Fission         Rocketry 
   ͼ      ͼ                                     
                                                              Ŀ
                                                                         
                ĳĳĳĿ              
                                         Nuclear_Power         Space_Flight  
                                                                           
                                                                           
                                                            Ŀ           
                                                                           
                                                          Plastics       
                                                                            
                                     ĳ            
                                                        
                                                  ͻ 
                                SuperConductor      Robotics
                                                   ͼ
                                               
                                       
                             ͻ
                             Fusion_Power
                             ͼ




