WILLIAM SIEMENS, F.R.S. 2QI 



oil to protect the bearing from the action of the water, and the 

 oil being the lighter fluid cannot be displaced by the water. The 

 drum F carries three or more flat blades KK, intended to produce 

 a resistance in the water increasing as the square of the velocity 

 of revolution, the effect of which is that the drum, which has a 

 tendency to revolve at a rate increasing more rapidly than the 

 velocity of the water, is caused to rotate at a speed proportionate 

 to the quantity of water passing through, whether at a high or 

 low velocity. 



The water having issued into the chamber C passes away by 

 the pipe L to the point of delivery. The spindle G passes upward 

 into the chamber M, which contains wheel work to reduce the 

 motion communicated by the drum and is also filled with oil. A 

 small spindle passes finally at a greatly reduced speed through a 

 stuffing box into the upper chamber N, containing the dial on 

 which the quantity of water that has passed through the meter is 

 indicated by hands in gallons or cubic feet. The details of the 

 counting apparatus have been described in the former paper. 

 The cup or dish forming the chamber M is made of stamped 

 brass and corrugated, in order to yield to concussions from the 

 water. 



Before entering the meter, the water has to pass through a 

 grating 0, which arrests any solid matter, and is made easily 

 accessible for the purpose of removing from time to time the 

 impurities that have collected, when it is found that the passage 

 of the water is obstructed. 



It is important to make the area of the inlet E nearly equal to 

 the collective area of the outlets of the drum F, but a little smaller 

 than the latter. If the area of the inlet were made larger than 

 that of the outlets, there would be a greater pressure within the 

 drum than in the surrounding chamber C, and some water would 

 escape unmeasured between the neck of the drum and the outside 

 of the inlet E ; on the other hand, if the area of the inlet were 

 made considerably smaller than that of the outlets, a leakage 

 would take place from the chamber C into the drum, because the 

 water passing through E would act in the manner of a blast or as 

 in Mr. James Thompson's jet pump. The area of the inlet should 

 accordingly be for the smaller meters 10 per cent., and for the 

 larger 5 per cent, less than that of the outlets, to allow for loss of 



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