METAL SURFACES AND LIQUIDS IN CONTACT WITH THEM. 
73 
adjustment of the valves to obtain exactly equal amounts of water through the pipe 
and jacket became very difficult and tedious. 
To remedy this defect, two meters were made according to suggestions made by 
Mr. Foster of Owens College, and these proved very successful. The form of the 
meter is shown in fig. 5, and consists of a cylindrical tin box, 14 centims. diameter 
by 7 centims. deep. The water enters at the centre A, and flows radially over the 
flat plate BC, then radially inwards, guided by the radial vanes to the central orifice, 
which is re-entrant. When in use the meter is always full, and the motion is very 
steady. 
The head is measured by the column of water in the small glass tube EF, and the 
flow read off on the scale GH, which is calibrated at intervals by experiment. It was 
found that on any re-adjustment of the water valves, the level of the water in EF 
almost instantly took up its proper position for the altered flow, so that it became an 
easy matter to set the two valves to give an equal flow of the desired amount. 
The circular orifices were made of the thinnest sheet Itrass procurable, soldered to 
brass plugs, which could be screwed into the bottom plate of the meter. A set of 
three pairs of orifices was made, and the scale calibrated for each by experiment. 
Method of Heating the Water. 
As it was necessary to be able to adjust the initial temperature of the jacket water 
and pipe water to any required value, two copper coils were made, out of |-" tubing, 
the length used being about 8 feet for each coil. These were contained in cast iron 
cylinders, which were connected to a steam boiler, and were provided with suitable 
cocks and drains. 
During every experiment it was found necessary to maintain the pressure in the 
boiler constant, as a variation of two pounds on the square inch in the boiler pressure 
had a considerable effect on the final temperature of the water passing through the 
coils. 
By using steam in the cylinders surrounding the coils at CO lbs. per square inch 
pressure, it was possible to raise as much as 25 lbs. of water per minute tlirough a 
range of 50° C. 
The arrangement of the heating coils is shown in fig. 4. 
Measurement of the Surface Temperature of the Pipes. 
In the preliminary experiments it was attempted to measure the temperature of 
the surface by means of a thermo-electric couple. As the wires had to be taken 
through the hot water in the jackets, considerable difficulty was experienced in 
insulating them, and although several attempts were made, consistent results could 
not be obtained, so that the method was abandoned. 
VOL. CXC.—A. 
L 
