In the western part of the country much knowledge has been gained by investigating and experimenting on this kind of spring water development, only there the springs have been made artificially by digging down to meet the underground flow of water. For example, in the Arkansas River Valley, California, where it was suspected that water was flowing underground, a trench was dug transversely across the valley, and at a depth of six feet sufficient water was found to amount to 200,000 gallons per day for each one hundred feet of trench. On the South Platte River, near Denver, much the same thing has been done, and in a trench eighteen feet deep, water is collected at the rate of a million and a quarter gallons per day for each one hundred feet of trench. Other examples of the same sort might be given. For a single house, the spring need usually only be extended by means of a short trench, and three-inch terra-cotta tile should be laid in the trench and surrounded by gravel and then covered over. The spring receiving water from these tiles should be inclosed, as will be described in a later chapter. _Supply from brooks._ Whenever a spring is not available and at the same time a supply of running water by gravity is determined on for a house, recourse is generally had to brooks which may find their way down the hillsides in the vicinity. In many instances the water in such brooks is practically spring water and is the overflow of actual springs. Where the brook is not subject to contamination between the spring and the point at which the supply is taken, the latter is as truly spring water as the former, and if a long length of pipe is saved, there can be no objection to the brook supply. On the other hand, it is suggestive, at least, of misrepresentation for a summer hotel or boarding house to advertise that their water-supply comes from springs when really it comes from an open brook miles away from the spring which may be indeed the origin of the brook, but with so many intervening opportunities for contamination that the pure original source is unrecognizable. There are two obvious drawbacks to the use of brooks: (1) that the quality of the water is, in many cases, objectionable, and (2) that brooks are very apt to dry up in summer on account of their limited watersheds. The discussion on the first point will be postponed to a later chapter, and we have now to consider the question of quantity only.