Brindley was no sooner installed as engineer of the works than he completely altered the duke’s plan. To construct the proposed canal—or ‘novogation,’ as Brindley has it—it was necessary to cross the river Irwell, and it was here that he first showed his marvellous courage and skill. The duke’s plan had been to drop the canal by a series of locks to the level of the river, and to raise it again on the farther side by the same means. But Brindley, who foresaw that locks would always prove a great hindrance to traffic, decided that the canal should not change its level, but should cross the river on a stone aqueduct. Nothing of the kind had ever before been attempted in this country, and, to ordinary minds, the idea of boats, laden with coals, sailing, as it were in mid-air, seemed preposterous. It must be allowed, to the everlasting credit of the duke, that, although somewhat uncertain in his own mind as to the result of the scheme, he nevertheless allowed Brindley to proceed. In spite of general ridicule, the works were commenced, the aqueduct was built; and derision was turned into amazement when the canal-boats passed over and the structure showed no sign of collapse. The packhorses were dispensed with, and the price of coal in Manchester fell to one-half. The success, both to the projector and the community, was so complete, that the duke at once sought further powers to extend the canal westward, and thus to open communication with the port of Liverpool. After much opposition from landowners and others, Brindley commenced this extension; but although no great engineering difficulties were encountered, the expenditure for some years had been so heavy that the want of money threatened to offer a serious obstacle to the completion of the scheme. The duke’s credit became so low that the greatest task of the week was the collecting of a sufficient amount to pay the wages of the labourers on the works; and it was only by much scheming and economy that the works were at length completed.