This section is from the book "Cyclopedia Of Architecture, Carpentry, And Building", by James C. et al. Also available from Amazon: Cyclopedia Of Architecture, Carpentry And Building.
The first duty of an agent is the strict and far reaching one of loyalty to his trust. In enforcing this the law looks not at the intent or effect in any given transaction, but at the tendency of such transactions in general, and at the policy of permitting a given course of dealing. Thus it is a general rule that an agent may not deal in the business of the agency for his own benefit, but that all the profits made in the business of the agency belong to the principal. A decision in accordance with this rule held that where one person employed another for hire to pursue and capture a horse thief, the principal was entitled to a reward offered for the capture effected by the agent. While an architect in the ordinary course of his professional duties does not act exclusively as agent of the building owner, yet in matters where he is not acting as arbiter between the owner and the contractor he is in general held to a duty of loyalty to his employer which is substantially that of an agent. Thus it sometimes occurs that dealers offer rebates to architects specifying their wares; such rebates undoubtedly belong to the owners, the owner being entitled to singleness of purpose in his interest on the part of the architect, and the latter being under obligation to obtain supplies at the lowest possible price and give his employer the full benefit thereof. The operation of the rule of agency is not defeated by a custom to the contrary, nor is an agent allowed to accomplish by indirect means what would not be permitted if done openly and directly.
Another duty of the agent is to obey instructions, and the agent is liable for losses incurred by his disobedience. "While the necessity of a sudden emergency may be a justification for the agent, in the use of sound discretion, in departing from his instructions without consulting his principal, on ordinary occasions an agent makes material and unauthorized departures from his original instructions at his peril. It is further the duty of every agent "to bring to the performance of his undertaking, and to exercise in such performance, that degree of skill, care and diligence which the nature of the undertaking and the time, place and circumstances of the performance justly and reasonably demand. A failure to do this, whereby the principal suffers loss or injury, con -stitutes negligence for which the agent is responsible."* The law holds an agent to the exercise of such care and skill as persons of common capacity engaged in the same business may be supposed to possess. In the case of an architect the law would presume, in the absence of anything to the contrary, that in giving his services, he warranted himself to possess in a reasonable degree, the knowledge and skill required for the work undertaken.
The principal is entitled to the personal knowledge and skill of his chosen agent, and the agent may not unless specially authorized, delegate to others the powers conferred upon him by his principal. But in the case of duties of the agent which are merely mechanical or ministerial, involving no elements of judgment, discretion or personal skill, power to delegate is implied. So the nature of the duty may be such as to require reliance upon others in performing it; and the authority of an agent will be so construed as to include the necessary and usual means of execution, so long as such means are not prohibited by express instructions.
*Mechem on Agency. p 329.