The results of the experiments at the Model Garden have never been published in full, and the author is indebted to Mr. George Bechmann, chief engineer of the sanitary department of the Seine, for information as to these valuable results. As visited in December, 1894, the Model Garden presented evidence of the many careful and systematic experiments carried out, although at that season of the year little idea could be formed of the relative benefits of sewage to different crops, for the reason that crops were not then growing. The following particulars as to the irrigation of Gennevilliers are derived from the report of Mr. Bechmann for the year 1893. According to the report, the area under irrigation has remained stationary at 776 hectares since 1891, in which year, as already stated, the entire available area was taken up. Of this area of 776 hectares, 6 hectares belong to the city of Paris and constitute the Model Garden and its dependencies. The remainder is composed of varioussized parcels which are 48722.65 the property of the individual cultivators,

33992.35

3$992.35

1876

24 509.90

1877

28605,70

1878

28/76.60

1879

29789.35

1880

32368.35

1881

33769.35

1882

1883

1884

33992.35

1885

33992.35

The sewage is distributed by means of a system of main and secondary channels, with a total length at the present time of 49,427.7 meters. The progressive increase in length of these conduits from the beginning to 1893 is shown by fig. 26. The distribution service is in charge of the agents of the city of Paris, who work according to a system, irrigating successfully the three belts into which the plain has been divided. The force having this work in charge consists of 3 foremen and 23 ordinary workmen, who perform all the labor necessary for a proper and successful distribution of the sewage. Foremen receive 170 francs per month and laborers from 145 to 150 francs per month.

The total volume of sewage distributed in 1893 was 33,421,299 cubic meters. Each hectare of the plain, therefore, received on an average a little more than 43,000 cubic meters, the distribution per acre being, thus, 625,293 feet. The amount actually distributed each month is shown by fig. 27, while the least area irrigated in one day varied from month to month as per fig. 28. From this figure we learn that the minimum area

tares per day in Sep- 3,500,000 tember.

Of the 6 hectares belonging to the city of Paris and included in the Model Garden, 3 hectares and 85 ares were rented in 1893 at an annual rental of 600 francs

per hectare. The re

mainder of the 6 hectares was devoted to various experiments,

3,000,000

2,500,000

2,000,000

1,500,000

1,000,000

500,000

J. F. M. A. M. J. J. A. S. O. N. D. FIG. 27.-Diagram illustrating distribution of sewage by months at Gennevilliers. The numbers denote cubic meters.

Mr.

principally to intensive irrigation, wherein from 80,000 to 130,000 cubic meters of sewage per hectare per year were applied. Bechmann states that the application of such large quantities of sewage is not prejudicial either to the purification or to the success of the crops. The experiments at the Model Garden have been di

150

125

100

75

50

25

J. F. M. A. M. J. J. A. S. O. N. D. FIG. 28. Minimum amount of sewage distributed per day by months in 1893. The numbers denote hectares.

rected specially for a few years toward the cultivation of nursery stocks of various sorts, and the results obtained are stated to have been remarkably good.

The cost of the irrigation at Gennevilliers is said to have been 0.0022 franc per cubic meter of sewage distributed. In our currency this would amount to 0.00043 cent per cubic meter.1 The purification attained during the year 1893, as determined by a series of analyses regularly made at the municipal observatory of Montsouris, continues to be absolutely satisfactory. Without referring to the degree of purification attained as indicated by chemical 1 The cubic meter equals 35.94 cubic feet, or 1.33 cubic yards.

analyses, we may merely call attention to the bacterial purification. According to the Montsouris laboratory determination, the sewage as it flows in the Clichy main contains 29,454,000 bacteria per cubic centimeter, while the water of the Asnieres effluent drain contains only 5,380 bacteria per cubic centimeter, and that of the Epinay drain 26,500 bacteria per cubic centimeter.

The foregoing is an exceedingly inadequate account of sewage utilization at Paris. The literature of the subject has grown very extensive, and whoever would familiarize himself with all that has been done at Paris must go through this large mass of literature in detail.

SEWAGE PURIFICATION IN THE UNITED STATES.

At the present time there are upward of 60 sewage-disposal plants in operation in the United States and the Dominion of Canada. The limited space here available will not permit an account of these works, but in a subsequent pamphlet of this series it is intended to give a brief description of a few of the more recent or more interesting establishments. Facts concerning many of these may be found in the columns of Engineering News and Engineering Record and in Sewage Disposal in the United States, which latter contains descriptions of and reference to works built in the United States previous to 1893. A complete discussion of existing American works would fill a large volume.

As examples of sewage utilization we may refer to Pullman, Illinois; Los Angeles, California; South Framingham, Massachusetts; Meriden and Bristol, Connecticut; and Plainfield, New Jersey. Intermittent filtration without any attempt at sewage utilization is also practiced at Marlboro, Brockton, and North Brookfield, Massachusetts; Summit, New Jersey; Pawtucket, Rhode Island; and also at a number of other towns. Examples of precipitation plants may be seen at Worcester, Massachusetts, and Canton, Ohio.

Much has been done toward advancing knowledge of sewage purification in this country. At the present time the scientific part of the subject is somewhat in advance of the practical application, and herein lies ground for criticism. The managers of American works have frequently failed to understand the importance of closely following rational theory. It is believed that with good management the American works can be quickly made to show as good results as can be obtained anywhere, for generally they have been well designed-a fact which may be set down to the credit of the engineers.