The Telegraph Key
The telegraph was the only long distance instant communication device until radio and other means came along. A telegraph key was the tool used to send coded messages, but why are there so many different models of telegraph keys?  What are the differences? What do they do? Can we just use any key as a telegraph key? What caused developing so many different designs? 
[Telegraph Key]
Material and instructions
The purpose of this project is to investigate and make a close observation of different telegraph keys and build a simple working model of a telegraph key.
Details of this project
More information or support for this project is available at members section of You may also find a Science kit for this topic at