20 MR. J. H. GRINDLEY ON AN EXPERIMENTAL INVESTIGATION* OF 



motion. In the experiments the quantities through the orifice were always relatively 

 small the orifice being a small one. 



In the first place, before making this point the subject of direct experiment, we 

 may remark that the maximum quantities of steam per minute in any two experi- 

 ments under the same initial conditions were not the same on account of the gradual 

 closing of the orifice by fine particles of dust. 



Thus Experiment 18, made under the same initial conditions as regards pressure 

 and temperature to Experiments 10 14, gave results which were not different from 

 those of the latter experiments, though the quantity of steam, when a maximum, in 

 Experiment 18 was only 1 Ib. in 40 minutes, while in Experiments 10 14 the 

 maximum quantity would sometimes reach 1 Ib. in 8 minutes, which would occur 

 when the orifice was clean as in Experiment 13. 



Similar variations in quantity and, therefore, in the energy of motion of the steam 

 occurred in other experiments under the same initial conditions in which, again, no 

 difference could be detected. 



The results obtained, therefore, would indicate that the effect of energy of motion 

 on the readings taken was too small to be noticed. To put the matter to a more 

 severe test, however, an orifice of more than three times the sectional area of the one 

 previously used was employed to repeat experiments at low initial steam pressures. 



In the first experiment made with this orifice, the quantity of steam through the 

 apparatus was so great that drops of water were carried through the orifice, being 

 the water from the steam condensed just before the orifice was reached. No definite 

 results could, therefore, be obtained as the condition of the wiredrawn steam seldom 

 left the saturated state. The maximum quantity of steam used in this experiment 

 was 1 Ib. in 2'1 minutes, the initial temperature being 303 F. 



The initial pressure was therefore reduced in the next experiment made with the 

 same orifice. The initial temperature was 262*5, the quantity of steam used per 

 minute being at least three times greater than that in Experiments 19 21, the 

 initial temperature in these experiments being 261-5. The experiment gave four 

 temperature readings which, when plotted, showed a mean deviation from the curve 

 drawn through the results of 19 21 of T2 3 F. ; as, however, the initial temperature 

 was 1 higher, the difference is not sufficient to show definitely any marked effect 

 of increasing the energy of motion of the steam at least threefold. 



As, however, the velocity of the steam was raised in these experiments up to the 

 point at which bubbles of water were carried through the orifice, it is impossible to 

 put a greater test on the apparatus to find the effect of the energy of motion of the 

 fluid on the temperature and pressure readings. 



The energy of motion of the steam, after wiredrawing, at the place where the 

 thermo-junction is placed to register its temperature, can also be approximately 

 calculated, and, for present purposes, it will be sufficient to take the actual reading in 

 the experiments at which this energy of motion will probably be greatest. On 



