14 ENGINE TESTS. 



in the bottom 6" or 8" square. With rectangular tanks this 

 system can be employed for any size of stationary engine 

 ordinarily met with. 



Where a meter is used for measurement care should be 

 observed that water is fed through it at a uniform rate, and the 

 instrument should be calibrated under conditions in every 

 respect like those of the test. One method of calibrating a 

 meter, which the author has found simple and fairly satisfac- 

 tory, is to arrange the piping on the outlet side with a valve 

 known to be tight, and provide, at a point between this valve 

 and the meter, a tee Avith a branch having a flexible hose 

 attached. A gauge is also connected to show the pressure. 

 The valve leading to the hose need not be of the full size of 

 the main line ; for under the conditions of the calibration it dis- 

 charges the water against a pressure much less than the work- 

 ing pressure, and, if the quantity is small, against practically 

 no pressure. The hose is carried to two empty barrels located, 

 preferably, outside of the building, where the water can be dis- 

 charged without doing harm; and there two workmen are 

 stationed to manipulate this end of the line. In making the 

 calibration, the stop valve in the main is closed, and the branch 

 valve leading to the hose is opened and so adjusted as to keep 

 the pressure at the working point. The pump or other appara- 

 tus for feeding is at the same time adjusted to give the working- 

 quantity of supply. This will be determined by timing the 

 readings of the meter for, say, one minute. When the proper 

 rate has been secured, the meter is read ; and at that instant a 

 signal is given to throw the hose into one of the barrels, the 

 water during the preliminary operations having run to waste. 

 When the first barrel is filled, the hose is quickly thrown into 

 the second one ; and while the second barrel is filling, the work- 

 men tip the first one over bodily and empty it. When the 

 second barrel is filled, the hose is quickly transferred back to 

 the first, and immediately the second barrel is tipped over and 

 emptied. This can be carried on as long as desired, depending 

 upon the size of the meter and the thoroughness required. The 

 last reading of the meter is taken when the last barrel becomes 



