AGREEMENTS MADE BY POST CONSIDERED. An offer communicated by letter is construed a continuing offer during every instant of time until it has reached the person addressed and a reasonable time has been given in which to accept or reject. It may he ithdrawn by the sender at any time before the letter of acceptance is mailed, but the notice of withdrawal must reach or be communicated to the person to whom the offer has been made before it is effective. The acceptance of an offer by post is complete when the letter of acceptance is duly posted, properly addressed and prepaid. The assent of the par ties to the terms is then complete, and the agreement binding on both, and this is so although a letter with drawing the offer has been written and postedprevious ly, but not yet received by the offeree. The accept ance makes the contract when posted, and it does not matter if the letter of acceptance fails to reach the of ferer.