Yes I am sure…
a birth is a point in time, but when only the year is known, that point must lie somewhere within the interval [1850‑01‑01, 1850‑12‑31]. The year is the interval, the birth is the point inside the interval.
And following the same logic:
If Fred is born “in 1850”, then he must have been born at some unknown point within that interval **.
** If you instead say he is born AFT 1850 , then he is born after that interval — not inside it.