The Author Explains
Dear Editor:
Am very much puzzled by the several apparent mistakes in two of the stories in the April issue of Astounding Stories. In "The World Behind the Moon," Mr. Ernst makes an error so obvious that it almost makes me believe that it isn't an error. Like doing a math problem and finding it so easy that you're sure that you have it wrong. Anyway, here is my problem; this is taken verbatim from the story: "At two thousand miles from the Earth there had still been enough hydrogen traces in the ether to give purchase to the explosions of their water-motor." Does the author mean to say that the explosions of the tubes have to have something to push against to have any action? (a) Has it not been proven actually and mathematically that the explosions of rockets and expanding gases are even more powerful in space? The space ship in this story was equipped with both bow and stern tubes; why not fire them to slow the ship down instead of waiting to run into some resistance?
(b) Also, when they landed they took some air-guns which shot bullets containing a liquid which exploded when heated by the passage of the shell through the barrel; then the author goes ahead and tells us that the planet was about as hot as the tropics. Such heat should explode the bullets, but it didn't. Why?
Mr. Ernst has his heroes do a lot of running around on that little planet.
(c) Since the planet is smaller than the moon, it hasn't much gravity and therefore can't retain a very heavy atmosphere, or one very thick. Anyone doing all that violent exercise would probably die of exhaustion before many minutes of it.
"Four Miles Within" was a good story, but I am unable to understand why they did not find a lot of stagnant air. Air that had lain stagnant for the time that cavern must have been closed would have killed the person who breathed it. Also, I would imagine that it wouldn't be safe to handle a chunk of radium like the characters in the story did; it's liable to burn. However, it probably wasn't pure radium, just pitchblende-bearing rocks.