: >,46 Profs. H. T. Barnes and E. G. Coker. [Nov. 4, 



to those on the tank. From the end of the tank a glass prolongation 

 C held the mercury thermometer placed and securely fastened 

 centrally in the tube. The glass tube was cemented into a brass tube, 

 connected with a screw-down valve D, for regulating the flow. From 

 the valve a pipe led to a two-way switch over E, provided with one 

 pipe to waste and one pipe leading to the double-coned copper measure, 

 shown at F. This measure had been very carefully calibrated by 

 Mr. T. P. Strickland some time previously. 



For small flows, where the time for filling the tank became 

 inconveniently long, a smaller vessel was used and the amount of 

 discharge obtained by weighing on a large bullion balance. For the 

 high temperature experiments, a worm pipe G was inserted in the 

 outflow so as to cool the water before it entered the measure. Water 

 was circulated continuously through the jacket by means of a 

 centrifugal pump H, operated by a Pelton water motor I. A gas flame 

 J, under the pump, served to regulate the temperature of the jacket. 

 A thermometer K was placed in the water circuit so that the tempera- 

 ture could be regulated at will and maintained a few degrees above or 

 below the temperature of the water flowing out from the tank. A 

 graduated disc L was provided on the valve, by means of which 

 a pointer on the valve gave an indication of the amount opened. 



During the greater part of the experiments, the temperature of the 

 tank was taken from a long-stem thermometer placed so that its bulb 

 reached to the centre somewhat below the flare on the pipe. It was 

 found that the temperature thus indicated differed but little from the 

 stream-line reading on the thermometer in the glass prolongation at 

 high temperatures, and was in practical agreement with it at the lower 

 points. For the majority of the experiments, an average head of 

 about 8 feet was maintained, sometimes running down to 4 feet, but 

 seldom getting as low as that. One filling of the copper measure 

 only lowered the head f of an inch, so that no constant level device 

 was necessary. The temperature of the tank could be raised to any 

 point up to 90 C. by means of a steam heater. A stirrer was also 

 fitted to the tank, but of course was not kept moving after the 

 temperature of the tank was once brought to a uniform state. 



The method of making an experiment was very simple. One 

 observer stood at the valve and regulated the flow until it was seen by 

 the reading that the stream-lines had completely disappeared, and the 

 other observer then switched over the flow into the measure and took 

 periodic readings of the temperatures. The time was taken on a 

 chronograph during the earlier runs, but was changed to a Frodsham 

 and Keen chronometer which had been carefully rated. The water in 

 the tank was always allowed to remain undisturbed for several hours 

 before taking an experiment. For the high temperature experiments 

 the tank was heated to about 90 and then allowed to settle. Over a 



