Nice #40, Jack!
I agree with Mike and Jan that the springs were added by a previous owner. Given that they serve no useful purpose, perhaps he just liked the look or possibly had it apart and could not find the correct screws and needed the springs as spacers to adapt longer screws. You can check the screw length against those on any other #5. If they are the correct original length I would suggest removing the springs and put it back as intended.
There is another possibility.... a former owner may have snapped an original screw off in the iron base and needed the spring to use an original length
screw.
The whistle is a replacement. Jensen was making these on steel bases with straight wood handles before he went to the hour glass wood handles.
Altogether a very nice engine.
Gil