He once gave a lecture at the Surrealists Exhibition in London in an old, deep sea diving suit.
He wanted to illustrate his subconscious mind in this way, but he did not foresee that he would have limited air access there. The audience didn't realize it until Dali passed out.
Tesla was a capable, bright student able to perform integral calculus by memory.
Of course, this aroused the disbelief of his teachers, who thought he was cheating. Finally, however, he finished his education scheduled for four years in three.
