314 Mr. Watt’s Observations on Basalt , &c. 
dignified with the name of columns, because they have occurred 
in lavas and in rocks of trap formation, they are utterly inade- 
quate to illustrating the formation of the more perfect basaltic 
prisms : they offer no means of accounting for the extreme 
regularity of the sides and the precision of the angles, for the 
articulations, for the close contact in which the perfect columns 
are placed to one another, nor for their mutual adhesion, which 
is so strong, that it often requires considerable violence to se- 
parate them. These facts are in absolute contradiction to all 
idea of retreat or contraction, and seem to me to coincide per- 
fectly with the explanation of their origin which I have already 
presumed to lay before you. 
I have the honour to be, &c. 
GREGORY WATT, 
