Mayor of Pittsburgh v. O'Neill

Per Curiam. All trades have their usages; and when a contract is made with a man about the business of his craft, it is framed on the bas|s of its usage, which becomes part of it, except when its place is occupied by particular stipulations. Now the witness had been a paver for thirty years; and he was called, as an expert, to speak-of the method employed by pavers to ascertain the number of bricks laid in a job without reckoning them by tale. He was allowed to prove how many of an ordinary size went to the, square yard; and from that the whole number could be ascertained by measuring the sides of the pavement, just as the whole number of shot in a pile can be ascertained by the number contained in the sides of the base. As an expert, therefore, the witness was competent. But it is said that the paving of the [344] top of the basin was to be done on the terms contained in tire written contract for paving the bottom and the sides. That contract, however, has no provision that would affect the general principle; and the evidence was consequently proper. Judgment affirmed.