72 THE LAW AFFECTING ENGINEEKS 



of work nine inches thick, and finding all materials, deducting 

 all lights." The lower part of the walls, to a height of 

 eleven feet, were of stone, two feet thick, the remainder of 

 brick, fourteen inches thick. It was held that evidence of the 

 usage of builders at the place to reduce brickwork for the 

 purpose of measurement to nine inches, but not to reduce 

 stonework, unless exceeding two feet in thickness, was 

 admissible ; and that, the proper construction of the contract 

 was that it provided only for the price of the brickwork, leaving 

 the stonework to be paid for as on a quantum meruit. As an 

 example of another usage mention may be made of an 

 American case, in which a plasterer, who worked at so much 

 a foot, was held entitled to prove a custom to the effect that 

 the whole wall including openings for windows might be taken 

 into account for this purpose. 



In Bank of New Zealand v. Simpson, 1900, A. C. 182, the 

 House of Lords laid it down that words with a fixed meaning 

 in a written contract cannot be explained by oral evidence to 

 mean something different from what they express ; but where 

 the words used are susceptible of more than one meaning, 

 extrinsic evidence is admissible to show what were the facts 

 which the negotiating parties had in their minds. So it was 

 held that where a written contract provided that the 

 respondent, a railway engineer, should receive extra com- 

 mission " on the estimate of 35,000 in the event of my being 

 able to reduce the total cost of the works below 30,000," 

 evidence was rightly admitted to show to what items of cost 

 the estimate related. 



13. How far a custom may be imported. The question 

 whether a contract is to be read and construed in the light 

 of a custom or usage depends upon several things. The 

 custom must be reasonable and certain. It must also be well 

 known not only to the immediate parties to the contract, but 

 generally (Kirchner v. Venus, 1859, 12 Moo. P. C. 361). 



14. Customs held to be valid. A number of customs or 

 usages are so well known that contracts are every day entered 

 into upon the footing of their validity. For instance, if a 

 manufacturer were employed to repair a machine, he would 

 have a lien on the machine for his proper costs and charges, 

 although nothing to that effect was said at the time of the 



