SfJt WILLIAM SIEMENS, F.R.S. 287 



tern below, capable of containing 1000 gallons, and accurately 

 graduated throughout. A set of pipes is provided that have been 

 proved to transmit given quantities of water per minute, under 

 the pressure from the upper cistern. From 8 to 12 meters to be 

 tested are coupled in a line, one behind another, to a pipe leading 

 from the upper cistern to the outlet of the meters ; the test 

 pipes are then alternately connected, a uniform quantity of water, 

 as shown in the cistern, is passed through each pipe, and the 

 number of gallons indicated on the different counters are noted in 

 a book opposite to the permanent number of the respective meters. 

 An extract from this book shows how nearly correct a measurement 

 is obtained. 



MR. SIEMENS exhibited specimens of his meters of the two 

 kinds of construction described in the paper, with specimens of 

 the castings for the spiral drums, &c. ; also the first meter he had 

 constructeed on that principle. 



He remarked that the mode adopted of insulating all the wheel- 

 work in oil, was a point of great importance practically in water- 

 meters, as wheels working in water were subjected to a deposit 

 taking place upon them, increasing their friction and causing them 

 to wear out ; and it was an essential qualification for a good meter, 

 that it should continue in constant action for a very long period 

 without perceptible wear or inaccuracy. The upper chamber filled 

 with oil was found to answer the purpose quite satisfactorily ; the 

 oil being lighter kept always in its place, and could not be dis- 

 placed by the water ; the spindle passing from the oil chamber was 

 ground in with a slightly conical shoulder. 



The CJiairman observed that there was great ingenuity shown 

 both in the principle and the construction of the meter. He 

 inquired how many of the meters there were at work ? 



J/r. Siemens replied that there were 200 or 800 of the screw 

 meters at work, of very different sizes and pressures, and abont 

 200 of the small meters on the BarkerVmill principle. 



In reply to remarks by various speakers Mr. Siemens observed 

 that the body of the meter was made larger in the area of passage 

 than the outlet, and therefore the velocity of the current was 

 slower through the spiral vanes of the meter than anywhere else ; 

 and there would be no practical difference of pressure between the 



