19

TABLE No. 18.

MERRIMAC RIVER AT LAWRENCE. DRAINAGE AREA, 4 452 SQUARE MILES. 1890 to 1906. Weekly data arranged in order of magnitude for full term.

22 23 24 25 26 27 28 29 30 31 32 33

22

0.716 0.743 0.763 0.790 0.826 0.865 0.899 0.934 0.991 1.045 1.114 1.160 1.231 1.300 1.355 1.420 1.485 1.577
0.720 0.743 0.764 0.792 0.837 0.865 0.900 0.935 0.994 1.046 1.118 1.161 1.234 1.302 1.359 1.421 1.486 1.577
0.721 0.744 0.766 0.794 0.839 0.867 0.902 0.947 0.999 1.053 1.121 1.161 1.235 1.307 1.367 1.423 1.486 1.580
0.721 0.744 0.772 0.795 0.841 0.869 0.902 0.951 1.000 1.054 1.123 1.163 1.244 1.313 1.367 1.429 1.490 1.583
0.722 0.745 0.773 0.795 0.845 0.870 0.903 0.953 1.001 1.067 1.126 1.169 1.249 1.313 1.370 1.430 1.493 1.590
0.722 0.745 0.773 0.795 0.847 0.874 0.903 0.966 1.004 1.073 1.127 1.173 1.251 1.316 1.375 1.433 1.502 1.590
0.724 0.751 0.774 0.800 0.848 0.878 0.910 0.968 1 007 1.079 1.130 1.181 1.252 1.316 1.387 1.438 1.504 1.592
0.726 0.752 0.775 0.802 0.849 0.879 0.910 0.971 1.009 1.083 1.135 1.195 1.260 1.319 1.394 1.442 1.517 1.595
0.726 0.753 0.780 0.802 0.853 0.886 0.911 0.972 1.015 1.086 1.138 1 197 1.268 1.319 1.394 1.443 1.519 1.596
0.727 0.755 0.780 0.807 0.855 0.886 0.913 0.972 1.017 1.092 1.142 1.198 1.272 1.319 1.398 1.444 1.530 1.597
0.729 0.756 0.781 0.809 0.858 0.888 0.915 0.973 1.025 1.095 1.142 1.204 1.275 1.319 1.400 1.452 1.532 1.600
0.729 0.756 0.781 0.809 0.859 0.888 0.925 0.974 1.029 1.098 1.143 1.204 1.287 1.327 1.412 1 457 1.536 1.604
0.730 0.756 0.783 0.809 0.859 0.888 0.925 0.977 1.034 1.098 1.144 1.208 1.291 1.328 1.413 1.458 1.545 1.608
0.731 0.757 0.783 0.810 0.861 0.889 0.928 0.980 1.035 1.101 1.148 1.210 1.292 1.333 1.414 1.477 1.545 1.608
0.731 0.758 0.784 0.813 0.863 0.891 0.928 0.985 1.036 1.108 1.148 1.211 1.295 1.335 1.414 1.477 1.548 1.615
0.733 0.759 0.788 0.821 0.864 0.894 0.928 0.989 1.039 1.110 1.149 1.218 1.296 1.344 1.416 1.477 1.548 1.619
0.740 0.760 0.788 0.825 0.864 0.895 0.929 0.991 1.041 1.110 1.157 1.222 1.296 1.353 1.417 1.485 1.569 1.622

0.726 0.752 0.777 0.804 0.851 0.881 0.914 0.961 1.016 1.082 1.136 1.190 1.266 1.321 1.391 1.447 1.520 1.597

3377

TABLE No. 19.

MERRIMAC RIVER AT LAWRENCE. DRAINAGE AREA, 4 452 SQUARE MILES.
1890 to 1906. Weekly data arranged in order of magnitude for full term.

1

2

1.626 1.785 1.895 2.017 2.128 2.280 2.431 2.565 2.786 3.017 3.323 3.639 4.199 4.519
1.634 1.802 1.902 2.019 2.133 2.283 2.432 2.568 2.823 3.053 3.356 3.661 4.217 4.562
3 1.634 1.804 1.903 2.026 2.169 2.289 2.440 2.571 2.830 3.084

4.565

5.111, 5.941

1.639 1.825 1.928 2.048

2.173

4.608

5.122 6.310

5

1.686 1.831 1.929 2.049

2.202

4.278

4.636

5.168

6.364

2 203

4.637

5.242 | 6.426

3.384 3.681 4.244
2.294 2.443 2.598 2.832 3.092 3.389 3.683 4.261
2.319 2.457 2.619 2.853 3.096 3.415 3.690
6 1.687 1.833 1.929 2.050
2.322 2.461 2.631 2.865 3.103 3.424 3.747 4.291
7 1.697 1.846 1.935 2.055 2.204 2.350 2.472 2.676 2.891 3.119 3.433 3.762 4.300 4.681 5.267 6.436
1.701 1.851 1.941 2.056 2.205 2.371 2.473 2.687 2.915 3.123 3.445 3.835 4.320 4.701 5.270 6.470
9 1.702 1.858 1.943 2.060 2.217 2.372 2.486 2.701 2.930 3.124 3.446 3.894 4.339 4.718 5.274
1.708 1.861 1.946 2.075 2.226 2.376 2.502 2.714 2.953 3.134 3.454 3.942 4.342 4.723 5.307 7.260
1.716 1.874 1.969 2.077 2.231 2.377 2.507 2.723 2.955 3.147 3.476 3.944 4.375 4.723 5.335 7.361
12 1.718 1.883 1.969 2.078 2.231 2.388 2.508 2.726 2.982 3.148 3.478 3.950 4.378 4.734 5.340 7.891
1.725 1.885 1.981 2.091 2.239 2.391 2.509 2.729 2.986 3.150 3.481 3.966 4.468 4.837 5.387 7.900
1.734 1.889 1.990 2.098 2.246 2.392 2.530 2.735 3.005
1.759 1.890 1.993 2.104 2.254 2.394 2.531 2.746 3.014
16 1.764 1.892 2.005 2.115 2.259 2.400 2.539 2.751 3.014 3.234 3.520 4.060 4.475 5.044 5.585 9.036
17 1.781 1.895 2.014 2.116 2.270 2.406 2.558 2.781 3.015 3.303 3.529 4.168 4.511 5.061 5.725 9.043
Av. 1.701 1.853 1.951 2.067 2.211 2.353 2.487 2.678 2.921 3.138 3.444 3.857 4.349 4.744 5.308 7.161

A GLANCE AT THE WATER SUPPLY OF PHILADELPHIA.

BY JOHN C. TRAUTWINE, JR., CIVIL ENGINEER, PHILADELPHIA, PENN. [Read September 23, 1903.]

INTRODUCTION.

Now that the New England Water Works Association has ventured so far out of its latitude as to hold its convention in a suburb of Philadelphia, it seems not inappropriate that some mention should be made of a water-works enterprise the inception and progress of which have greatly exercised some of the inhabitants of that city.

I have been asked to present a statement of the "progress and present condition" of the Philadelphia filtration plant; but, in order to do this satisfactorily, it may be well to give, first, an outline of the works in general.

With the same object in view, I find myself tempted to volunteer also a bit of the history of the Philadelphia water supply, even at the risk of indulging in some personal reminiscences, and thus fighting some of my own battles o'er again.

EARLY CONDITIONS.

The public water supply of Philadelphia has always been drawn either from the Schuylkill River alone or from the Schuylkill and Delaware rivers, the Schuylkill being a tributary of the Delaware and entering that stream at the lower end of the city.

The Schuylkill rises in the anthracite coal regions of Pennsylvania, about 100 miles above Philadelphia, and has a watershed of about 1900 square miles. The Delaware rises in the southeastern part of New York state, a little north of Port Jervis, where New York, New Jersey, and Pennsylvania meet. Its watershed, above Philadelphia, has about 8 000 square miles, and is about 180 miles long, from north to south, and in general from 20 to 70 miles wide from east to west.

Prior to 1854 the city of Philadelphia covered only about two square miles, being comprised within the nearly rectangular area bounded by the Delaware River on the east, by the Schuylkill