context: During the period in which the negotiations were being conducted, Tesla said that efforts had been made to steal the invention. His room had been entered and his papers had been scrutinized, but the thieves, or spies, left empty-handed. He said that there was no danger that his invention could be stolen, for he had at no time committed any part of it to paper; the blueprint for the teleforce weapon was all in his mind.
question: Where was Tesla's invention located?