8 W. & L. E. GURLEY, TROY, NEW YORK 



accuracy. The energies of some of the foremost engineers of 

 the world have been given to this work, and as a result both 

 methods and appliances have been highly perfected. 



For many years W. & L. E. Gurley have been the leaders 

 in the manufacture of instruments for the measurement of 

 water. At the Panama Pacific International Exposition they 

 were given the highest award for Hydraulic Engineering 

 Instruments. 



Every part of these instruments is constructed from carefully 

 selected material, and is accurately made and finely finished 

 by experienced workmen in the Gurley Factory, which has been 

 producing precision instruments and equipment for over 

 seventy-five years. They consist of Engineering and Surveying 

 Instruments, such as Transits, Levels, Compasses, Plane Tables, 

 Alidades, Sketching Cases, Leveling Rods and Stadia Rods; 

 and Standard Precision Weights and Measures. 



The methods commonly used in carrying on water measure- 

 ments are described in standard text books, to which frequent 

 reference has been made in preparing this Manual. We are 

 indebted to prominent hydraulic engineers for suggestions and 

 photographs, and grateful acknowledgment is hereby made to 

 these friends for their co-operation, as well as to the authors 

 quoted in this book. 



W. & L. E. GURLEY 



