In 1877 the Melbourne Tramway and Omnibus Company operated a network of cable trams. These are trams which are moved by grabbing a loop-shaped cable installed under the road, which was driven by a stationary steam engine in a pulling house. It had several advantages over over other forms of transport available at the time: it was more reliable and humane than horse power (horses which pulled trams were usually overloaded and whipped); it was quiet, safe and non-polluting, unlike steam traction; however the equipment was very complicated and expensive. When electric motors became more powerful and reliable, electric trams (as we know them today) took over.