Till! THERMODYNAMIOAL PKOPE!:TI1> OK siTKIMlKATKD STK.VM. 



15 



\' error was the radiatiou of heat from the channel containing the wiredrawn steam, 

 tliis being remedied by the construction of a steam jacket. 



The apparatus as finally used, and as described in Section IV., was ready for 

 experiments in November, 1897, and as often as circumstances permitted experiments 

 were made until July, 1898. The first experiments made, however, gave results of 

 very little value, since it was proved that sufficient time had not been allowed for the 

 steady condition of pressure and temperature to become established before taking 

 olwervations, and henceforward jmrticular attention was given during any experiment 

 to obtaining a few temperature results at pressures covering a wide range of pressure 

 ratio. 



Among the many sources of experimental error encountered was one which for 

 some time affected to a great extent the observations taken at very low pressures 

 below the orifice, and which caused a great deal of trouble during the experiments. 

 Thus, when observations at low pressures were being taken and continual pumping 

 required to maintain those pressures, the temperature of the superheated steam could 

 not be obtained with any degree of consistency. 



The cause of this inconsistency appeared to be connected with the amount of 

 pumping necessary, and in later experiments, where the low pressures could be 

 maintained with little or no pumping for about half an hour, it was found that 

 consistent readings could be obtained, and only readings obtained under these 

 conditions are accepted and find place in the table of results given below. 



The corrected results of twenty-eight experiments made with saturated steam at 

 temperatures varying from 240 to 380 F. are given in the accompanying Table TIL, 

 T, and PI l>eing the initial temperature and pressure respectively of the saturated 

 steam before wiredrawing, j>\ being taken from REONAULT'S steam tables, and T 4 the 

 temperature of the wiredrawn steam corresponding to the pressure p t . 



TABLE III. 



