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 original contract is invalid,1 as because of mistake,2 as where a contract for excavation is made under a mistake as to the character of the ground to be excavated,3 or because of fraud,4 a subsequent contract increasing the compensation to be paid for the performance of the original contract, is supported by sufficient consideration. If the original contract 'was valid at the outset, but it has subsequently been discharged by breach, the act of the party who is not in default in waiving his right to avoid all liability under such contract is consideration for a new promise.5
5 Kelly v. Bliss, 54 Wis. 187. 11 N. W. 488.*
6 Delta County v. Blackburn. 100 Tex. 51, 93 S. W. 419; Brown v. Ever-hard, 52 Wis. 205, 8 N. W. 725; Magill v. Stoddard, 70 Wis. 75. 35 N. W. 346; Ruege v. Gates, 71 Wis. C34. 38 N. W. 181.
7Ruege v. Gates. 71 Wis. 634. 38 X. W. 181.
8 McGill v. Stoddard. 70 Wis. 75. 35 N. W. 346.
9 Brown v. Everhard. 52 Wis. 205, 8 N. W. 725.
10 Delta County v. Blackburn, 100
Tex. 51. 93 S. W. 419. This case, how-ever, turned upon the constitutional power of the county, and there was in fact a modification changing the interest from seven per cent. for twelve years to three per cent. for twenty years.
1Osborne v. O'Reilly. 42 N. J. Eq. 467, 9 Atl. 209; John King Co. v. Louisville & Nashville Ry., 131 Ky. 46, 114 S. W. 308 [rehearing denied (Ky.), 116 S. W. 1201].
See $ 335.
2 John King Co. v. Louisville & Nashville Ry.. 131 Ky. 46, 114 S. W. 308