By it, I shall be deprived, for the space of a year, both at once of my house and of your vessel.

By it, you will make use of both.

If, in the absence of this clause, the bargain was just, for the same reason the clause is injurious to me.

It stipulates for a loss to me, and a gain to you.

You are requiring of me a new service; I have a right to refuse, or to require of you, as a compensation, an equivalent service." If the parties are agreed upon this compensation, the principle of which is incontestable, we can easily distinguish two transactions in one, two exchanges of service in one.