INTERACTION OF THE SCIENCES 139 



ical analysis confirmed Hall's judgment of the simi- 

 larity of these two igneous products. 



Still later Hall introduced chalk and powdered 

 limestone into porcelain tubes, gun barrels, and tubes 

 bored in solid iron, which he sealed and brought to 

 very high temperatures. He obtained, by fusion, a 

 crystalline carbonate resembling marble. Under the 

 high pressure in the tube the carbonic acid was re- 

 tained. By these and other experiments this doubt- 

 ing disciple confirmed Hutton's theory, and became 

 one of the great founders of experimental geology. 



It remained for William Smith (1769-1839), 

 surveyor and engineer, to develop that species of 

 chronology that Hutton had ascribed to organic re- 

 mains in the solid strata, to arrange these strata in 

 the order of time, and thus to become the founder of 

 historic geology. For this task his early education 

 might at first glance seem inadequate. His only 

 schooling was received in an elementary institution 

 in Oxfordshire. He managed, however, to acquire 

 some knowledge of geometry, and at eighteen entered, 

 as assistant, a surveyor's office. He never attained 

 any literary facility, and was always more success- 

 ful in conveying his observations by maps, drawings, 

 and conversation than by books. 



However, he early began his collection of minerals 

 and observed the relation of the soil and the vegeta- 

 tion to the underlying rocks. Engaged at the age of 

 twenty-four in taking levelings for a canal, he no- 

 ticed that the strata were not exactly horizontal, but 

 dipped to the east " like slices of bread and butter," 

 a phenomenon he considered of scientific significance. 

 In connection with his calling he had an opportunity 



