I was 11 years old in 1935, and an avid movie goer. I was absolutely fascinated by the idea of digging a tunnel from England to America, no more unbelievable at that time, than building a tunnel under the Channel from England to France which was actually begun by Napoleon in 1802 and completed in the 1990's. It is now over 70 years since I saw the film and cannot remember much of the detail except that the lead actor was Richard Dix who if my memory serves me correctly was the chief engineer. I don't know why it is referred as science fiction as many movies over the years have to do with construction projects, and I saw it as a real happening. Perhaps towards the end of this century it may be accomplished.