There had to be an accurate observing instrument (Maskelyne had the sextant) and there must be an accurate method for observing local time.
Kwakumele kubekho isixhobo sokuqwalasela esichanileyo (UMaskelyn wayenesekstanti), kwaye kwakumele kubekho inkqubo echanileyo yokuqwalasela ixesha lendawo ekuyo.