by decimal 0025 (0.0025) of a penny per kilowatt hour in respect of each complete shilling by which the Basic Wage as hereinafter defined is greater or less than twelve pounds one shilling (£12 1s. 0d.) per week and shall be increased or decreased by decimal 015 (0.015) of a penny per kilowatt hour in respect of each complete shilling by which the price of large coal to Muswellbrook Coal Co. Pty. Limited or Mepco Pty. Limited at Muswellbrook is greater or less than 51/9½d. per ton such increase or decrease to apply for the same period or periods as the increase or decrease of the Basic Wage and the price of large coal respectively shall operate.
It is clear I think that the variations referred to in cl. 2 are treated as variations in "the Supplier's costs". Of course in one sense they fall outside this description, because, the supplier does not pay the wages for the labour nor pay for the coal used in the generation of the electricity supplied. Reference however to the agreement between the supplier and the generating companies discloses the existence of like clauses. In consequence an increase or decrease in the basic wage or the cost of coal to the generating companies automatically affects both the price that the supplier pays for electricity and the price that it charges the purchaser. In a real sense, and, in the sense of the agreement, cl. 2 does relate to "the supplier's costs". It is apparent, therefore, that what the agreement does is to provide (1) for the automatic variation of charges, in the event of specific changes in the basic wage and specific changes in the price of coal paid by the generating companies; and (2) for the right of the supplier to vary charges if its costs of carrying out its contract with the purchaser should vary in other respects in the course of its doing so. This latter provision may in certain circumstances give rise to problems. The right of the supplier to vary charges is not in terms limited to passing on increased or decreased costs. It may be, although this is unlikely, that any variation in unidentified costs during the period of the contract, would give the supplier an unrestricted right to vary charges. Recognition that there are questions of construction implicit in cl. 5, and, that in agreeing to it in the form in which the clause appears the purchaser may have been improvident, does not mean that the clause is meaningless, nor, does recognition that, in particular circumstances, there may be more than one view about the true effect of the clause. Ambiguities of the sort that I have been discussing, do not however involve that kind of uncertainty which defeats the intention of the parties to make a binding contract; viz., the use of language which, as a matter of construction and not mere speculation, cannot be given any one meaning rather than another.