Steam and screw propeller took a long time to displace sail in coastal bulk trades: 60 years compared with the 20 years needed for steam and the paddle to dominate coastal liner trades. As this thesis confirms, conquering the bulk trades was a much more difficult undertaking. To offset far greater capital and running costs, the developer of the steam bulk carrier could offer only that his steamer, largely independent of weather and tide, would carry significantly more cargo in a given period than a sailing vessel. This thesis demonstrates how, to fulfil this promise, many obstacles had to be overcome, including the high cost of iron hulls and steam engines, the inefficiency of early steam engines and boilers, the water ballast problem, slowness of discharge, archaic port practices, and physical constraints of ports and waterways. The findings suggest that, in the rise of the steam bulk carrier, the role of the railways should be diminished, and that of the gas industry accentuated. The impact of rail competition on the London collier trade was no more than a pinprick when the first screw collier was building, and the coal market's subsequent growth was so strong that the steady increase in rail-hauled coal barely dented the tonnage delivered by sea from the north east. On the other hand, without the gas industry's demand for large, regular and guaranteed deliveries, the coal interests would probably not have encouraged the development of the screw collier when they did.