I am reading "Relativity: The Special and General Theory" by Albert Einstein, and in orden to continue reading with full understanding, I would like someone to please clarify one thing for me (or most likely more than one). In the section dealing with "The Principle of Relativity (in the restricted sense), Einstein explains that "In the general laws of nature... ...with reference to K, the magnitude and direction of the velocity of the carriage would necessarily play a part." He goes on to exemplify saying that "the note emitted by an organpipe placed with its axis parallel to the direction of travel would be different from that emitted if the axis of the pipe were placed perpendicular to this direction." I would like to know if I am understanding this right. Is the fact that the organ's note will sound different, depending on the position of its axis, due to the doppler effect? Is this difference what he calls in the following paragraph the anisotropic property resulting from the difference of the position of the axis of the organpipe? If this was the case, then I understand that if the axis of the organ is parallel to the direction of travel of the carriage, then the organ would be moving along with the carriage and the note would sound normal to a listerer on the carriage but different to someone on the enbankment. Conversely, if the axis of the organ is perpendicular to the direction of the carriage then the note would sound normal to a listener in the enbankment but different to someone traveling in the carriage. Am I in the right trend of thought? Or did I go off the course? I would appreciate your comments.