Psychologists suggest that to cure cruelty

parted with John Lennon and left the Beatles

3.Although Paul McCartney started out in rock music

1. 
   he was more successful in other forms
   
2. 
   he found success in several other areas as well
   
3. 
   he was a classically trained musician
   
4. 
   all songs for the Beatles were written by John Lennon
   

Long before men learned how to fly, they sent objects soaring through the air. The arrow dates from the Stone Age. The ancient Chinese flew kites. The early inhabitants of Australia invented the boomerang, the blades of which they carved in the shape of an airfoil. As early as the Middle Ages, men of scientific mind prophesied human flight. About 1250, Roger Bacon, an English friar, suggested the orthopter, a machine that flaps its wings like a bird. He also conceived the balloon, proposing "a hollow globe filled with ethereal air or liquid fire." Some 250 years later, the great Italian artist and scientist Leonardo da Vinci studied the flight of birds. About 1490, he drew sketches for flying machines, also of the orthopter type. Leonardo made drawings of a propeller and a helicopter. An Italian monk, Francesco de Lana, in 1670 proposed a vacuum balloon. Four spheres, from which air had been exhausted, were to support a car equipped with oars and a sail. He overlooked the phenomenon of atmospheric pressure, however, which would have crushed the spheres. Not until a hundred years later was the first balloon flown successfully in public. In 1783, J. Etienne and Joseph M. Montgolfier inflated a big paper balloon with hot which rose 6,000 feet.