Attributing Einstein

I'm such an Internet-based human being now that I don't quite know how to authoritatively source a quote attribute to Einstein: The wireless telegraph is not difficult to understand. The ordinary telegraph is like a very long cat. You pull the tail in New York, and it meows in Los Angeles. The wireless is the same, only without the cat. It sounds genuine. You can find this quote all over the place. But I want to cite the newspaper, book, or other account it comes from. It can't have come from thin air. I'd dig up some print biographies, but I have doubts that this quote would be indexed in the back.