When the light bulb was cheaper and better, we ditched kerosene.
For such buried deposits boring is cheaper than sinking.
Through the advent of German and American fur sewingmachines since about 1890 fur work has been done better and cheaper.
In the case of the cheaper and more abundant minerals, such as coal and iron ore, and of large deposits of low-grade ores, the extent and character of the deposit can generally be determined by surface examinations at comparatively small expense.
This is in general a cheaper and quicker method of development for inclined deposits than by a vertical shaft, and it has the added advantage that much information as to the character of the deposit is obtained as the shaft is sunk.