AND ITS APPLICATION TO MR. B. TOWER’S EXPERIMENTS. 
181 
and right will both act on the brass to the right, and as these will increase as the 
surfaces approach, the distance JI must be exactly such that these components 
balance the resultant friction, which by symmetry will be horizontal and acting to the 
left. 
It thus appears that when the brass is unloaded its point of nearest approach will 
be its middle point. This position, together with the curves of pressure, are shown 
in fig. 14. 
Fig. 14. 
As the load increases the positive vertical component on the right of GH must 
overbalance the negative component on the left. This requires that IT should be to 
the left of O. 
It is also necessary that the horizontal components of pressure and friction should 
balance. 
These two conditions determine the position of H and the value of JI. 
As the load increases it appears from the exact equations (to be discussed in a 
subsequent article) that OH reaches a maximum value, which places H nearly, but 
not quite, at the left extremity of the brass, but leaves JI still small as compared 
with GH. 
For a further increase of the load H moves back again towards O. 
In this condition the load has become so great that the friction which remains 
nearly constant is so small by comparison that it may be neglected, and the condition 
of equilibrium is that the horizontal component of the pressure is zero, and the 
vertical component equal to the load. 
