Riddle: The higher I climb, the hotter I engage, I can not escape my crystal cage. What am I?
This riddle might seem difficult to you at first but do not worry, you may find the answer easily after thinking about it or even if you cannot find you will understand its logic after you see the answer of it.
Since this thing engages the hotter when climbs higher, and it cannot escape its crystal cage, there are not many options what it could be. Thermometers has a liquid in them, and that liquid elevates when the room gets higher and this liquid also kept in a glass cage like system to prevent people from poising because of it. Therefore, the answer of this riddle is mercury in a thermometer.
The answer is: Mercury in a thermometer.