Wrought Iron when Heated and then Cooled. 



401 



The subjoined figures (half the full size) show the changes pro- 

 duced on the 9-inch cylinders after every five heatings. (Experi- 

 ments 2 and 4.) 



Fig. 22. 



12" Cylinder, 9" high, £" thick. 

 Vide fig. 4. Cooled by ^-immersion. 



Fig. 23. 



12" Cylinder, 9" high, i" thick. 

 Vide fig. 7. Cooled by f -immersion. 



No. 1. External surface, original form. No. 1. External surface, original form. 

 2. „ „ after 5 coolings. 2. „ „ after 5 coolings 



3« » » » 10 n o. ,, „ „ 10 „ 



4. „ „ „ 15 „ 4. „ „ „ 15 „ 



5. » „ n 20 „ 5. ,, „ „ 20 „ 



