duty put pumping plants on a new basis of efficiency and capacity. Since then the changes have been still more notable, higher duties being obtained by pumps of a tenth the dimensions and cost, now chiefly centrifugal pumps, driven by steam turbines or electric motors. Internal combustion engines have also come to the front, especially for smaller capacities, and crude oil is used in such engines as the Diesel. Until 1870 there were no water filtration plants in the United States, as the term is now understood, but some of the surface supplies then in use were passed through so-called filters or strainers of gravel, charcoal or sponge. Infiltration basins and galleries were used also. In 1870 Poughkeepsie and in 1874-5, Hudson, N. Y., built slow sand filters of the English type, which stood alone in the United States until modified slow sand filters were built at Lawrence, Mass., in 1893. Meanwhile in the late 80's the earliest rapid or mechanical filters were built. In 1897 there were about 100 rapid, but only a dozen or so slow, sand filters in use on public water supplies in America. In 1925 there were about 587 rapid and about 47 slow sand filters in use, with a total capacity of approximately 5000 million gallons per day. Chlorination dates from 1908. It is now used on nearly all surface supplies, whether filtered or not. Ownership of works has seen sweeping changes since the 16 privately- and 1 municipally-owned plant at the close of the eighteenth century. The accompanying table shows the swing to public ownership of works during the nineteenth century up to 1895 and the best available figures for later years (some 70 or 75 per cent public in 1924), but it does not indicate the far more rapid increase in the relative populations supplied by municipal and private works. Populations for 1890 on works of the two classes of ownership in that year, ascertained with care for the Baker, 1891, "Manual of American Water-Works" showed a total population supplied of 22,678,350, divided 15,018,522 public and 7,659,802 private or about 62 to 34 per cent, for the United States. For Canada the figures were a little over a million people supplied, of which 81.5 were on muncipally-owned works. Official Dominion statistics for 1915, given elsewhere in tabular form, show a total of 528 works divided 396 to 132 or 75 to 25 per cent between public and private ownership. Today (1925) it may be assumed that at least 95 per cent in Canada and 85 to 90 per cent in the United States of the people having water supplies are served by municipally-owned works. Total Water supplies of the United States, its Possessions and Canada Based mainly on information from engineers of state and provincial departments of health as of 1924 or so near that date as to be approximately correct. Surface Under ground Unknown Joint or Total places supplied. Forty states and the District of Columbia reported a total of 7651 places having water supplies, most of the figures apparently being for some date in 1924 but some as early as the close of 1922. These states had 2698 places supplied with water at or about the close of 1896. The gain in places supplied from 1896 to 1924 (approximately) was 4953, or over 180 per cent. The states not reporting in 1924, with the number of places in each supplied with water in 1896 were as follows: Arizona, 5; Nebraska, 92; Nevada, 10; North Dakota, 10; Ohio, 154; Pennsylvania, 445; Washington, 51; Wyoming, 15; total, 782. (The Water-Works Resources Inventory of Pennsylvania compiled by the State Water Supply Commission from returns collected in 1914, showed 676 municipalities having public water supplies.) Assuming the same percentage (180) of growth from 1896 to 1924 in places supplied for the eight states as is shown for the 40 states there would be for the whole United States about 9850 places supplied in 1924. The separate table for possessions of the United States, shows 250 places supplied (with no report for Alaska), thus bringing the estimated total places supplied in the United States and its possessions to 10,100, in round numbers. For Canada an estimate in the number of works (not places supplied) in 1924 follows: The three provinces for which 1924 data are available reported 282 works in 1924, against 219 in 1915; an increase of 63 works or about 30 per cent. Allowing the same percentage gain for the other six provinces would bring their combined number of works to 402, the total for all Canada to 684, against 528 in 1915. Presumably 700 to 750 places are supplied by these works. Numbers of works. The number of water-works in the United States in 1924 is unknown; many privately-owned works supply two or more places, with a maximum of 55 places supplied by one New Jersey company, and some cities supply outside territory. Estimates for Canada are given just above. Ownership. Thirty-eight states and the District of Columbia report ownership, embracing 7347 places supplied. Of these 5077 or 70 per cent, are supplied from municipally-owned works, 2194 from privately owned, and 76 have supplies of mixed or unknown ownership. If the 70 per cent of municipal ownership holds good for the whole United States, then about 7000 places are supplied from municipal and about 3000 from private works. Of the 250 supplied, reported in the possessions of the United States, 80 per cent are publicly owned. Canadian water supplies are nearly all publicly owned. Sources of supply. For 36 states and the District of Columbia, having a total of 6937 places supplied, the source of supply is reported, at least in part. The division is 2331 from surface, 4148 from underground sources, and 458 either mixed or unknown. Dropping the latter, of 6479 places, 2331 use surface water and 4148 underground water, or 36 and 64 per cent respectively. If data for populations supplied and water consumed were available probably the percentages would be much more than reversed. Canada has more surface than underground supplies. In the earlier years surface water supplies were relatively more common than now. "The Manual of American Water-Works" for 1888 gave the sources of supply for 1591 works in the United States (not places; but there was little difference between the two then). Of these works 907 or 57 per cent supplied surface and 684 or 43 per cent ground water. Although many private water companies supply more than one community (up to 55 in one case) there are but few "parent companies," or corporations owning and controlling many local water companies, as in the gas and electric utility fields. The largest parent water company known controls some 30 companies, located in 15 states. TABLE 2 Growth in number and changes in ownership of United States water-works since 1800 * Since this table was originally compiled one additional works, privately owned, in existence before 1800, has come to light, but as the figures up to 1896 have been before the public for many years and the change is so slight, with percentages not affected after the first few lines, it has not seemed worth while to remake the table. † Estimated. The investment in water works runs into billions and is rapidly increasing. The total volume of reported water works "contracts let" in the Construction News Section of Engineering News-Record totaled $61,445,000 for 1924 and was slightly higher for 1923, the figures including no jobs under $15,000 each, but taking in work reported as to be done by force account. Water bonds sold in 1923 totaled $86,831,000 and in 1922, $93,693,000. These figures, combined with the facts that many water works jobs run less than $15,000, |