May 21, 1915] 



SCIENCE 



767 



sembling humus soil in forests, also inofEensive. 

 This has been made possible by the recent exten- 

 sive introduction of ImhoflE tanks. Quite recently 

 it has been found that a daily mechanical agita- 

 tion of the sludge and always maintaining its 

 alkaUnity, materially hastens the decomposition. 



Operation and Efficiency Eeports from Water and 

 Sewage Purification Plants: Ealph B. Irwin. 

 In Pennsylvania the state commissioner of 

 health is required by law to give a permit for the 

 construction of all water purification plants sup- 

 plying water to the public for domestic purposes 

 and for all municipal sewage treatment plants. 

 To intelligently issue a permit for the construc- 

 tion of such plants it is necessary to have detailed 

 information concerning the eiiiciency, manner of 

 operation and construction of existing plants. 

 The commissioner has, therefore, created a section 

 in the engineering division which, under the di- 

 rection of the chief engineer, inspects and tests 

 plants already in operation. 



Operation and efficiency reports should be sub- 

 mitted to the commissioner of health: 



1. That the commissioner may know accurate 

 records are being kept by each plant. 



2. To give information for answering com- 

 plaints from those served. 



3. To assist in locating the cause of water-borne 

 disease apparently due to public water supplies. 



4. That information may be at hand from all 

 parts of the state, thus forming a clearing house 

 for information from plants treating similar 

 waters or sewages and make it possible to indi- 

 cate the most efficient and economical method of 

 treatment when considering improvements, or the 

 construction of new plants. 



5. To allow checking results from one plant with 

 another to show inaccuracies or carelessness. 



6. To give information for interpreting results 

 of .analyses submitted by plants, those served, or 

 results of samples analyzed at the commissioner's 

 laboratory. 



7. To give information upon which to base sug- 

 gestions for the prevention of waste of chemicals, 

 wash water, etc. 



8. To assist in judging the efficiency of opera- 

 tors in charge of plants. 



9. To have records at hand showing when in- 

 spections and tests are necessary and to assist in 

 this work. 



At the present time in Pennsylvania there are 

 115 water filtration plants and 91 sewage treatment 

 plants in operation. Also, there are a large num- 

 ber of chemical dosing plants installed for the dis- 



infection of dangerous water supplies and insuffi- 

 ciently treated sewage. 

 The New York Sewage Disposal Experiments and 



Plant at BrooTclyn, N. Y. : George T. Hammond. 



The experiment plant described in this paper 

 was authorized by the Board of Estimate and Ap- 

 portionment of the City of New York, $50,000 

 being provided to cover the cost. One of the most 

 difficult sewage disposal problems which the city 

 must solve is afforded by the rapidly progressing 

 pollution of Jamaica Bay — a tidal reservoir 19.28 

 square miles in area and very shallow, the situa- 

 tion of an important oyster industry. The popu- 

 lation contributing sewage to this bay is 250,000 

 persons, of whom 210,000 are ia Brooklyn. The 

 sewers are on the combined plan and discharge 

 18,000,000 to 22,000,000 gallons of dry-weather 

 flow into the bay daily. Storm-water flow from 

 the sewers at times reaches over 1,000 cubic feet 

 per second and is very foul. One of the principal 

 purposes of the experimental plant is to find the 

 best means of treating this sewage. 



The plan of the experimental plant provides for 

 pumping the sewage to an elevated supply tank, 

 from which it is fed by gravity to the experimental 

 units. The amount of sewage used by the plant is 

 about 1,200,000 gallons per day. The experimental 

 plant includes three ImhofE tanks of varying size 

 and depth; six sprinkling filter beds; one tank- 

 aerator for treatment of sewage with compressed 

 air supplied by an air compressor; one siphon- 

 aerator, which treats sewage by compressed air, 

 which is supplied by the flowing stream of sewage 

 through a hydraulic air compressor siphon; one 

 gravel strainer, or roughing filter; four settling or 

 sedimentation tanks; six secondary sedimentation 

 tanks; ten sludge drying beds of the ImhofE type. 

 Various types of screens, including a Eiensch- 

 Wurl screen. Various experiments are also pro- 

 vided for the disinfection of sewage effluents and 

 for various methods of treating and disposing of 

 sludge and screenings. All of the units of the 

 plants are constructed on a working scale, each 

 one large enough for testing the actual operation 

 conditions of a full-size plant. 



Some Considerations Affecting the Disposal of 

 Sewage at Seaside Eesorts: Marshall E. Pugh. 

 For a distance of approximately one hundred 

 and twenty-five miles the coast of New Jersey has 

 an almost continuous line of summer resorts, soma 

 large and some smaU. Some of the considerations 

 theoretical and constructive, affecting the disposal 

 of sewage at seaside resorts may be briefly stated 

 as follows: 



