Where the authority is limited to the performance of a single act, or accomplishment of one transaction, the agent so acting is called a special agent;3 as where an agent is vested with authority to purchase a coach horse, or where the agent is such for the purpose of making a single mortgage of real estate. The special agent's power runs to the performance of some special act, and his authority must be strictly followed out as directed by the principal. The special agent may also be particularly limited, in the manner of performance of the transaction he may have in hand.