The direct system, commonly called the Holly Plan, does away with reservoir and stand pipe, and delivers the water directly into the mains under a pressure usually fifty pounds per square inch for domestic use, which is increased to one hundred pounds when fires occur. In the Holly Plan, a reserve power is used for fire purposes, besides mechanical device for regulating and controlling the variable pressure. In either the stand pipe or direct system, a reserve power should be provided equal to the largest daily consumption. From a compilation of general information concerning water-works of the United States and Canada, published by the Holly Manufacturing Company in 1878, we arrange the following: 188 cities and towns use steam-power for water supply. 104 “ have gravity works “ 32 “ use water-power “ 10 “ have gravity and steam works “ 27 “ use steam and water-works “ 2 “ have gravity, steam, and water-powers “ Of the above number of pumping works-- 139 have reservoir system. 98 have direct system. 16 have stand-pipe system. 4 have direct and reservoir combined. 1 has the three systems combined. 1 has stand-pipe and direct combined. The expense of pumping water by steam and water-powers, also the practical yearly duties of various pumping engines, are given in the tables on pages 61 and 64, compiled from annual reports for 1880: PRACTICAL DUTIES (WITHOUT DEDUCTIONS) OF PUMPING ENGINES (YEARLY AVERAGE). (_From Annual Reports of 1880._)