Simplify the following text for a Grade 6 native English-speaking person.
Original: In 1742 he bought Marvels Mill at Northampton and converted this to a cotton mill , probably the first water-powered spinning mill in the world .
Simplified: In 1742 he bought Marvels Mill at Northampton and made this into a cotton mill . This was probably the first water-powered spinning mill in the world .