The replacement of the decrepit bridges occasioned Mr. Dickson no little perplexity, but this work became all the more urgent, as the original structures could not withstand the heavier locomotives and trains that were introduced by the British company. One of the most difficult undertakings of this character was the erection of a massive masonry arch bridge in three spans upon the rack system of the Petropolis branch. Each span is of 50 feet, and the work was complicated by being on a curve of 80 metres, or about 266 feet radius. It had to replace a trestle bridge, and reconstruction had to progress without interfering with traffic. Another notable piece of work which he completed successfully was the erection of a single steel girder bridge of 160 feet span across the Parahybuna River. Owing to the velocity of the current and the great depth of water, false-work was quite out of the question, so the steel-work had to be erected on shore, rolled out, and launched into position, being held in check by cables, which proved a trying ordeal owing to the current. When brought into position between the abutments, the steel-work was lifted by means of jacks, the temporary nose was dismantled, and the span lowered until it rested in the desired position upon its supports. [Illustration: [_See page 224_ THE ROCKBOUND SHORE OF LAKE SUPERIOR SEVERELY TAXED THE ENGINEERS IN THE BUILDING OF THE CANADIAN PACIFIC RAILWAY At places, construction averaged as much as £70,000, or $350,000, per mile.] Occasionally the advance of the railway has been resented by the inhabitants. For instance, when it was decided to carry the railway across the Parahybuna River at Campos, the populace of the latter town considered it an unwarranted intrusion. They were urged that the railway bridge would cause their trade on the waterway to shrink to infinitesimal proportions. Thereupon the inhabitants raided the railway, and zealously set to work to destroy everything destined for the bridge. The situation looked ugly, but the authorities took stern measures and quelled the riot, though not before damage to the extent of £40,000, or $200,000, had been wrought. This bridge is one of the most important upon the whole system. From end to end it measures 1,113½ feet, divided into six through truss spans supported upon five pairs of piers in the waterway.