[51] Journal für Gas- u. Wasserversorgung, 1894, 185.
[52] The method of making this determination was given in the American Chemical Journal, vol. 12, p. 427.
[53] Some of the companies secure some ground water which they mix with the filtered water, and this is included in the quantities for the separate companies, but is excluded from the totals for all the companies by years.
[54] Exclusive of gravity supplies.
[55] Not in use.
[56] Under construction.
[57] Not in use.
[58] Under construction.
[59] Not in use.
[60] Under construction.