Convert this sidereal time interval into a mean time interval by always Subtracting for the proper number of hours, minutes and seconds as per Table 8, Bowditch.
"Lectures in Navigation"
Ernest Gallaudet Draper
The Distance of towns from the place of starting to the terminus is expressed by the figures which accompany them on each side of the margin; while the distance of any two towns on the same route from each other is found by Subtracting their marginal figures on either side from each other.
"The South of France--East Half"
Charles Bertram Black
It's nothing but adding an' Subtracting, this gum-shoe work.
"The Voice in the Fog"
Harold MacGrath