preposition problem.

1. "In longitudinal waves atoms and molecules of the medium will vibrate along the direction of the propagation of the wave." -- my question is, in the line, 'along the direction' is it okay or should I write along with the direction?
2.In transverse waves atoms and molecules of the medium will vibrate ' along perpendicular of the direction of the propagation of the propagation of the wave' -- the marked part doesn't sound right to me,is it okay?if not then please help me to correct it.
Thank you in advance.