For all you curious people a "gravity filter" is used by some water utilities for the treatment of raw water.  There can be several layers of sand, with fine sand at the top and course sand at lower layers.  Below these can be found layers of fine to course gravel.  At the very bottom of the filter is an underdrain. When David worked for a couple of well contractors he helped in the rehabilitation of several small municipal water treatment plants.  He also had the privilege of servicing production well pumps at three large steam power plants, and a vertical, multistage, centrifugal condenser pump in the sub-basement of a small municipal power plant. 

 Two of David's greatest finds on eBay were; Water Power Engineering, by Barrows, and a late 1920s map showing the service areas of early North American electric utilities.  In the book are several technical drawings of early hydroelectric power plants utilizing "open flume" type turbines and "umbrella" type alternators.  David has also found several rare photographic postcards showing some of Nebraska's early electric light plants. 

Kathy found one or two discontinued Precious Moments figurines to replace some that were damaged several years ago.  She has also purchased some Disney DVDs via eBay.  When Kathy was gaming in the virtual world, she purchased goods for that activity on eBay.