Hi, I have a research question focusing on the historical development of the telephone. However, I have to write it with emphasis it's dependence principles of magnetism. So far, I have not found anything to relate the two topics. I also must include 1. a reference to at least one person who contributed to the development of the telephone 2. a description of the general scientific principles upon which the operation of the telephone designed by the person in number 1, is based. 3. a direct description of how the person in question 1 used the principles related to magnetic fields in their design. So far, I have only found either one topic, or the other. I have no idea where to look for a person who used this principle to develop the telephone. Could someone help me out? Thanks.