6071
Joseph Henry improved it in 1828 by placing several windings of insulated wire around the bar , creating a much more powerful electromagnet which could operate a telegraph through the high resistance of long telegraph wires .
 Joseph Henry
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: location, person, organization 
Text: {0} 
Answer:
 Joseph Henry