It thus appears that there is a second set of readings, involving a different cnlculation.  The second set supposes the Sun to be in the 10th degree of Leo, his altitude to be 56°, and his declination 18°; the difference, viz. 38°, is the complement of the latitude.  Either set of readings suits the sense, but the one in the text agrees best with the former latitude, viz. 51° . 50'.