A few years ago I wrote about how in 1842 the time for ushering in the Sabbath was determined by half hour intervals (link). They had pretty good clocks, but no one said "light candles at 7:21." It was, light candles at 7 for a couple of weeks, and as it got later, you'd light at 7:30, and so on.
I found something very, very interesting. Same city - London - fifty years later. In his Jewish Standard humor column Israel Zangwill printed a letter he says he received from Shabbat ("Shobbos") himself. Or herself, since the Sabbath is a queen. Maybe. (Malka vs malkah, who can tell?). This cynic tends to think that it was Zangwill himself who wrote it, but what do I know.
In any case, the Sabbath wanted to call attention to the fact that three separate sources gave three separate times for the end of the Sabbath. That December 20th of 1890, one said 4:30, one said 4:41, and one said 4:49.
No, the end time is not the same as the beginning. But what I am thinking of is the precision of the numbers. Interesting.