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In 1767 , he conjectured that the force between charges varied as the inverse square of the distance , saying : In 1769 , Scottish physicist John Robison announced that , according to his measurements , the force of repulsion between two spheres with charges of the same sign varied as x-2 .06 .
 person: John Robison
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: location, person, organization 
Text: {0} 
Answer:
 person: John Robison