The Historical Comparison of Players Arpad Elo described (chess life 1962) his ratings as 


  "the measurement of the position of a cork bobbing up and down on the
  surface of agitated water with a yard stick tied to a rope and which
  is swaying in the wind".


Thus the Elo Ratings system is more a measure of Chess players' relative strength against contemporaries rather than one with a historical context.

Is there a way to adapt the Elo system to give it historical context or is there a superior 
way to compare the relative strengths of players throughout history?
There is Chessmetrics, and it attempts to assign inflation adjusted ratings, even create elo-type rating for players of earlier period.

I am personally not a big fan of trying to compare great players across time. But it could be useful if you want to see who the top 10 players were in 1910 to 1920 time period.