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.
If the vendor instead of treating nonpayment of one instalment as a discharge, sues to recover such instalment, the contract is so far severable that he may recover any instalment due without waiting until he delivers all the instalments.1 In a jurisdiction in which the seller may avoid because of the default of the buyer in paying an instalment, the seller may not only treat the contract as discharged, but he may also recover for goods delivered up to the time at which he has elected to treat the contract as discharged.2
If the contract provides in express terms that the seller may cancel the contract for default in any payment, full effect is given to such provision;3 and the fact that the contract further provides that each instalment is to be treated as an independent sale, does not prevent the seller from treating the contract as discharged as to future instalments because of the buyer's default in paying for instalments which have already been delivered.4
 
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