Although in it states that he had discovered the sine law of refraction of light before 1597, in fact we now know that the precise date of Harriot's important discovery was July 1601.
Kahit na sa estado na ito niya natuklasan ang sain batas ng repraksyon ng liwanag bago mag-1597, sa katunayan na namin ngayon na malaman ang tiyak na petsa ng Harriot's mahalagang pagkatuklas ay Hulyo 1601.