226 



Trans, Acad. Sci. of St. Louis. 



The work done on a number of other trips has been sim- 

 ilarly reduced. All give very satisfactory results. A few in 

 which the effect of wind was least, have been used to check 

 the constant of Newton's equation. The results of the 

 observations are shown in Fig. 4, which is the same in char- 

 acter as Fig. 3. The different curves are indicated by Roman 

 numerals, which correspond to the number of car-lengths 

 from the locomotive tender to the point of observation. For 

 example, curve I represents observations made one car-length 

 from the tender of the locomotive. The horizontal line rep- 

 resenting the limiting pressure is also marked I. Similar 

 explanations apply to the other curves of Fig 4. The curve 

 of Fig. 3 is reproduced in Fig 4, where it is indicated by the 

 numeral IV. Additional data concerning these curves are 

 given in the adjoining table. 



Remarks. 



No wind. 



No wind. 



Light following wind. 



Light head wind. 



No wind. 



The column headed curve gives the number of the curve in 

 Fig. 4, and also the number of car-lengths from locomotive 

 to the point of observation. The next column gives the 

 V mean square velocity of the train. The third column gives 

 the number of observations of /?, to obtain a mean p, for 

 each of the eleven positions of the collector. In the final 

 column the remarks: No wind, means a very light wind, 

 variable as regards velocity and direction. It was thought at 

 the time of making the observations that it was not appreci- 

 able as a factor. 



A very large amount of work which has been done has not 



