The development of portland cement and widespread use of portable steam power in the 1800s contributed to the increased popularity of concrete. By the late 1800s, there were an extraordinary number and variety of mixers available. Some of the more popular types included the following: The portable gravity-feed concrete mixer was one of the earliest types of mixers. Cement, stone and sand were placed into a hopper on a raised platform. The materials mixed as they fell down a chute, and struck a series of steel pins and deflectors on the way down. Water was introduced through a spray pipe located midway down the chute. The cube mixer consisted of a cubical steel box revolving on a horizontal shaft passing through the diagonal corners of the box. Water was introduced into the mixture through the hollow support shaft. Le Messurier's concrete machine was used extensively in England before the turn of the century. It had two essential components: a turntable of hoppers on a cart, and a mixer and elevator on a wagonlike frame. The ingredients were distributed from the hopper, traveled up the elevator and were mixed with water at the mouth of the mixing drum. Auger and paddle mixers were of a linear design, featuring a mixing chamber that the concrete ingredients flowed through, and either an auger or paddles to mix the ingredients. Water was usually added around the middle of the process.