In this case by cup it probably actually refers to a pint glass of water (two measuring cups), but in any case not an exact measurement, so it doesn't make sense to give exact measurements. Its describing the vessels of transportation, not the amounts.
In this case by cup it probably actually refers to a pint glass of water (two measuring cups), but in any case not an exact measurement, so it doesn't make sense to give exact measurements. Its describing the vessels of transportation, not the amounts.