12. As we have already mentioned, the learned Judicial Commissioner chose to concentrate on the single word "exploitation" torn out of its context. The word "exploitation" taken by itself, could have been used to describe and confer only such general powers as may be needed for the working or exploitation of the mine. But, the earlier parts of the document show that the main purpose of the document was to give power to Thakker Junior to represent Mr. Sequeira not only in litigation and financial affairs but "to draw up and sign" various "documents and correspondence." It is true that the powers to sell is not specifically mentioned in the document. The nature of the documents and the correspondence which Thakker Jr. could sign on behalf of Mr. Sequeira is also not clarified. Instance of particular kinds of business to be transacted by the agent in the course of "exploitation" of the mine are given, such as "acquisition of petrol, gun powder, train, transport vehicles, machines, furniture and other instruments used in mining industry. It is difficult to see how any documents even for these special purposes could be signed without a power to buy and sell on behalf of the Sequeiras, Furthermore, the power expressly includes giving of "import and export orders." Now, the conduct of a business so as to give necessary orders for purposes of exporting and importing must, we think, by a necessary implication, include the power to sell what is excavated from the mine to be exploited. Otherwise, how could iron ore be exported? It is a well-known rule of construction that powers necessary and incidental to the effective exercise of the powers conferred will be implied.