This section is from the book "The Law Of Contracts", by William Herbert Page. Also available from Amazon: Commercial Contracts: A Practical Guide to Deals, Contracts, Agreements and Promises.
Whether an alleged alteration has been made or not,1 when it was made if at all,2 and whether the adversary party consented to such alteration or not,3 are all questions of fact. Whether an alteration is material or immaterial is a question of law. It is therefore error to leave such question to the jury.4