This is the link in which contex can be seen.
https://books.google.com.tr/books?id=t-DecO7W9vYC&pg=PA1&lpg=PA1&dq=A+horizon+slopped&source=bl&ots=3bNgywmyIB&sig=bOdJ7-njsiAcztC2WaV1fry12VA&hl=tr&sa=X&ved=0ahUKEwjFprKpxYjaAhURalAKHfDSCPAQ6AEIKjAA#v=onepage&q=A horizon slopped&f=false