Coolant flow

The Robertshaw invention patent applied for in 1957 granted in 1959, not exactly the latest modern technology!

https://image-ppubs.uspto.gov/dirsearch-public/print/downloadPdf/2872117

Good explanation, disassembly and pictures (even though the article relates to a 351 Cleveland) of the Robertshaw thermostat from the article:

Robertshaw Ford 351c Cleveland Thermostat