or SEXAGESIMAL Fractions, fractions whose denominators proceed in sexagecumple ratio; that is, a prime, or the first minute = \( \frac{1}{60} \); a second = \( \frac{1}{3600} \); a third = \( \frac{1}{216000} \). Anciently, there were no other than sexagesimals used in astronomy; and they are still retained in many cases, though decimal arithmetic begins to grow in use now in astronomical calculations. In these fractions, which some call afro-nomical fractions, the denominator being always 60, or a multiple thereof, is usually omitted, and the numerator only written down: thus 4°, 59', 32", 50''', 16'''' is to be read, 4 degrees, 59 minutes, 32 seconds, 50 thirds, 16 fourths, &c.