About: http://webisa.webdatacommons.org/213925121

Property	Value
http://www.w3.org/1999/02/22-rdf-syntax-ns#type	http://www.w3.org/ns/prov#Entity
http://www.w3.org/ns/prov#value	Referring now more in detail to the drawing, Fig. 1 is a vertical cross section through a portion of a well showing in elevation therein a heater constructed in accordance with this invention.
http://www.w3.org/ns/prov#wasQuotedFrom	google.com