EXPLANATION OF PLATES 381 



Plate 55. — Curves of Cooling — Narrotv Effective Contact Zone 



This diagram is similar to plate 54, except that a contact zone is shown in dashes, 

 and also the curve of plate 54, marked 1, and the point where it coincides with 

 the temperature of the margin in this case. Scales are the same as in plate 54. 



