If atmospheric conditions changed, these balls could have become obsolete.
Lots here and I'm not done reading it all, but I can't miss an opportunity to add more potentialities to the speculation. I would also suggest that perhaps the material the balls are made of could only "maintain a charge" for a finite amount of time.
It also seems possible that some of the accounts and depiction are from a later time where knowledge of the original use (and material) for these balls was lost, but they were ornamentally put on because "that's just how you build a ship!"
I'm coming to the idea that we are actually looking at very different types of ball
Agreed completely. Also though, it doesn't seem so ridiculous to me that some of these balls could have once (also?) generated light and in degraded state still be viable for radio transmission.
Daymarks were particularly important form early years until the 1920’s, permitting the lightship to stand out in a crowd, and to be set apart from other vessels or terrain features in the vicinity. Most of the lightship daymarks were ball shaped – large metal hoops, and circular or oval lattice structures to reduce wind resistance. These were mounted near one or both of the mastheads, and were painted a distinctive color.
That's a good example of how the balls, if once able to light up basically unassisted, could become ornamental. Are daymarks added to differentiate or is it because of daymarks that the ships are able to be identified?
It does appear that they are some kind of aquatic caution sign, in our timeline at least.
Appreciation to the posters in the thread who submitted some examples of ways to utilize the conditions present to generate power of some kind.
To circle back around the idea that maybe "atmospheric" changes rendered this tech inoperable, I alternatively suggest that maybe we don't have easy access to the materials used. Perhaps elements that are rare or deemed dangerous now are the missing piece which largely prevents modern recreation.
The rare earth elements are all metals, and the group is often referred to as the "rare earth metals." These metals have many similar properties, and that often causes them to be found together in geologic deposits.
That's interesting, right? They're rare, but they're grouped together?
Rare earth metals and alloys that contain them are used in many devices that people use every day such as computer memory, DVDs, rechargeable batteries, cell phones, catalytic converters, magnets, fluorescent lighting and much more.
So if you annihilated New York City, I bet future miners would find all sorts of rare earth metals grouped together... consider what that could mean for our current extractions.
Finally, should add this last part, in case anyone wants to point out that these elements aren't "rare" per se:
Rare earth elements are not as "rare" as their name implies. Thulium and lutetium are the two least abundant rare earth elements - but they each have an average crustal abundance that is nearly 200 times greater than the crustal abundance of gold. However, these metals are very difficult to mine because it is unusual to find them in concentrations high enough for economical extraction.
So they may be relatively plentiful, but it is certainly beyond the average human being with the technology currently available to them to extract them, so obtaining such metals would be solely at the mercy of the market effectively making them "rare" in the most practical sense.
More at the link, as I feel I've probably strayed from the original topic: