I think Tesla knew what he was doing, and he has mentioned on several occasions the need for a properly tuned system, indeed I find it hard to believe that he would have been able to generate 100ft streamers by simply throwing more power at it.
Chris,
Tesla measured his sparks in a different way than we do today. He measured all around the sparks or followed every twist and turn across the entire head of sparks and arrived at such figures. In reality his sparks were never more than 33 feet long or so.