750 



MR J. D. HAMILTON DICKSON ON 



along the Tait-line, by means of small circles. The complete note of their observed 

 values of dE/dt is given in Table III. to show how the work was carried out ; the 

 process has already been described. Here, again, the closeness between the theoretical 

 curves and the observational points corroborates the theory very strongly. 



Table III. 



Deviation 

 in mm. 



4 

 4 

 4 

 4 

 4 

 4 

 4 

 4 

 4 

 4 

 4 

 4 

 5 



Upper 

 Temperature. 



78 



66 



45 



23 

 2 



18 



41 



63* 



84 

 101J 

 121 

 136 

 150* 



Lower 



Temperature. 



35 

 12 



H 



21 



39 



62 



79 



98 

 118 

 138 

 158 

 168 

 181* 



Readings for 

 the Tangent. 



181 



+ 432 



70 

 195 



+ 200 

 + 420 



90 

 203 



+ 210 

 + 3931 



110 +220 

 169* + 396 



110 



199 



+ 260 

 + 313 



170 



209| 



+ 280 

 + 2081 



250 

 143 



+ 290 

 + 130 



250 

 94| 



+ 370 

 - 54 



440 

 316 



+ 250 

 + 29 



340 

 393 



+ 250 

 + 96* 



210 

 410 



+ 250 

 + 151 



120 



408^ 



+ 250 

 + 1861 



70 

 387 



+ 250 

 + 232 



10 +250 



Temperature 

 of Contact. 



561 



39 



19| 



1 



20* 



40 

 60 



80f 



101 



120 



139* 



152 

 166 



100 x tangent. 



-227-0 

 -205-0 



- 180-76 

 -152-8 

 -113-8 



- 77-4 



- 44-0 

 + 5-8 



+ 58-5 

 + 106-4 

 + 151-6 

 + 185-9 

 + 238-1 



German Silver. 



German silver was examined in 1903, and by any means then at disposal appeared 

 to give a parabola with no slope in its axis. On resuming the work at the present time 

 a " sheared " curve was drawn to test this point finally, namely, the A-curve on fig. 6. 

 The mid-points of a series of horizontal chords, parallel to the short line a on the diagram, 

 were marked, and, beyond a slight displacement of three about the middle,* they are seen 

 to lie very closely on a vertical straight line. As an additional test, the mid-points of 

 another series of sloping chords, parallel to the short line b on the diagram, which makes 

 an angle with the axis of t whose tangent is "5, were plotted ; they, too, show complete 

 absence of slope, thus demonstrating the curve to be a parabola with vertical axis. 



* The photographic reduction has rendered this displacement not visible in fig. 6. See Note, p. 788. 



