306 KANSAS CITY REVIEW OF SCIENCE. 
ity supply works for New York and for Boston, between 1830 and 1840, were 
such as can not be greatly improved, even at the present day, except in minor 
-details. 
About 1850 the substitution of light wrought iron pipe, lined inside and out 
with hydraulic cement, for cast iron, at greatly reduced cost, was found to be 
practicable in many cases, and the formation of companies to manufacture and 
lay such pipes, introduced a commercial element into the matter of water supply 
and led to the construction of many works. 
Improved forms of pumping machinery, which performed a fair duty at small 
expense for construction and maintenance, were designed and their manufac- 
ture became a special business. 
The careful analysis and investigation employed in the construction of the 
works for the supply of Brooklyn, between 1850 and 1860, resulted in a more 
decided advance, in both theoretical and practical science, than had hitherto 
been made, the effects of which were seen during the succeeding decade in im- 
provements in pipe manufacture, in engine building, in reservoir construction 
and in maintenance of works. 
Between 1860 and 1870, a further impetus to water works construction, was 
given by the vigorous prosecution of an enterprise for building entire works for 
direct supply, by pumping into the mains without the intervention of a reservoir. 
The success attending this enterprise, owing to the small first cost of construc- 
tion and to shrewd management, created competition, the result of which has 
been to force the adoption of scientific methods and the employment of skilled 
engineers, and as a consequence there has been great improvement in the types 
of machinery and in economical working. 
The pumping machinery of large cities has also been greatly improved; the 
duty now required, and uniformly maintained, being at least fifty per cent. 
greater than it was thought possible to obtain twenty years ago, or than is now 
furnished by the less costly ‘‘commercial engines,” of which two firms alone 
have built 242 for 168 towns, with an aggregate pumping capacity of 734 millions 
of gallons per day. 
The construction by Mr. Chesbrough of a submarine tunnel for two miles 
under Lake Michigan, to furnish water for Chicago, was one of the boldest en- 
gineering feats of this country. Its successful completion was followed by the 
construction of several similar works. 
On the Pacific coast, the use of unprotected wrought iron pipe for convey- 
ing great distances, and under great pressure, has proved very successful. 
During the past ten years, the most important work executed, has been the 
enlargement of the gravity supply for Boston, by the construction of a conduit 
of masonry, in the designing and erection of which the latest and most perfect 
methods have been followed. The subjects to which particular attention has 
been paid by engineers during this period have been the efficiency of pumping 
machinery, the capacity of gathering grounds, the preservation of the purity of 
water, and the prevention of waste by consumers. 
