New answers tagged lighting
There is no problem having your machinery, whatever it is exactly, working for you on shabbos. if someone left it on before shabbos, there would be no problem with any sort of bulb as long as no one is the direct or indirect cause of the flickering. Essentially the only time you're 'ovair', "guilty" so to speak, of breaking shabbos is when you actively ...
I used the Super Wicks this year, but found that some burned with very little output of light. They would stay lit long after the ones that worked as expected since they were consuming oil at a much slower pace.
Old shuls in Europe have these plaques as well, but without the lights. Is your question when (and why) lights were added, or when these plaques were first used? I recall from Medieval Jewish History classes that the concept/importance of Yahrtzeit was popularized in the aftermath of the Crusades.
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