During the 1860s Willis, Gann, and Co. dropped out of the New Zealand trade, while many of the big American-built wooden clippers of Pilkington and Wilson's White Star Line and the Black Ball Line, as well as ships of Houlder's Australian and New Zealand Packet Service, were frequent visitors to Dunedin and Lyttelton. But by the end of the decade Shaw, Savill, and Co. and the Albion Line had the United Kingdom – New Zealand trade to themselves. This monopoly gave rise to much dissatisfaction among importers and exporters alike who held that freights were too high. The result was the formation in Christchurch of the New Zealand Shipping Co. which was registered in January 1873 with an authorised capital of £250,000 with the object of “providing increased facilities for the New Zealand trade”. The first ships owned by the New Zealand Shipping Co. were the small iron, full-rigged ships Rangitiki of 1,188 tons, and the Mataura, Waimea, and Waitara, each of about 850 tons, purchased in 1873. Twelve ships of from 1,000 to 1,100 tons were built during the next two or three years and two others were bought subsequently. The company also employed many chartered vessels to cope with the boom in the cargo and emigrant traffic during the 1870s, as did the Shaw, Savill, and the Albion Lines. The Albion Line also built 12 notable clipper ships. During the flood of emigration in the 1870s no fewer than 93 ships arrived in New Zealand in the 12 months 1874–75 with 31,785 passengers, an average of 340 a ship. The great majority travelled in sailing ships, but in 1874 the steamer Mongol brought out 253 and the steamer Atrato 762, including 280 children. The Dutch steamer Stad Haarlem, of 2,729 tons, arrived in 1879 with some 600 emigrants and returned to London with a full cargo and a full complement of passengers.