144 W. & L. E. GURLEY f TROY, NEW YORK 



cessfully in the city of Atlanta, Ga.* and the sewer departments 

 of many other cities are interested in this method of obtaining 

 an accurate record at a reasonable cost of the amount of sewage 

 handled. See Fig. 76. 



Weirs have been installed at appropriate places in some 

 systems, with an automatic water stage register to keep a record 

 of the depth of sewage on the crest of the weir. The objection 

 is sometimes raised that the introduction of a weir in the lim> 

 <>t flow may cause an accumulation of sludge deposits back of 

 the weir. This may be provided for by making an ample 

 outlet to the weir chamber through a quick opening valve by 

 which the contents of that chamber may be rapidly and easily 

 discharged. 



In the design of sewage disposal plants the quantih <>f 

 sewage to be handled by the plant is one of the control linn 

 factors. This factor may be determined by the methods iiuli- 

 cated, but it should be noted that the information required is 

 not such as may be obtained overnight, but that its collection 

 will likely extend over a considerable time. Therefore, riti - 

 contemplating installations of this kind should be forehanded 

 in the matter of obtaining data. 



SOUNDINGS AND TIDE CAGES 



When conducting soundings for hydrographic surveys from 

 which to make charts of tidal waters, it is necessary to keep a 

 record of the stage of the tide so that the soundings, which are 

 taken to the surface of the water, may be referred to a perma- 

 nent datum. Recording water stage registers have been used 

 successfully on such work. Thev also find a similar use in 

 keeping a record of stage on tidal rivers. 



NAVIGATION CANALS 



It is frequently desirable to keep a record of the flow of 

 navigation canals. Because of the quantity of water used at 

 the locks, the slope of the water surface varies from time to 

 time, so that a record from a single recording register is not 

 successful. In such cases the method that should be used i- 

 that explained in detail by Messrs. Hall, Pierce, and Hall, in 



By Mr. Warren E. Hall, M. Am. Soc. C. E., District Engineer, U. 8. 

 Geological Survey. 



