The English literature is very clear that Joiners did know the benefits of adjusting the cap iron to suit the operation and ability to control tear out. Modern Practical Joinery by George Ellis (1902) is very clear at page 6 and 7 of the book. I have read other books of this time including USA books which also identify the advantage with precision. Later commentators such as Wearing and Joyce also state the advantages.
It is very easy to look at a statistically insignificant selection of surviving planes bought from eBay and draw a conclusion that the trade did not know based only on how the plane was last set. But as a matter of written record the Joinery trade writing on the subject is clear precise and correct. Surely the contemporaneous written evidence of the trade is a better guide to the state of knowledge.
In my experience, as an apprentice in the 1970's, the shop foreman would have a collection of old reference books that would come out when the combined experience of the shop was beat or struggling to find a solution to a problem.
It is very easy to look at a statistically insignificant selection of surviving planes bought from eBay and draw a conclusion that the trade did not know based only on how the plane was last set. But as a matter of written record the Joinery trade writing on the subject is clear precise and correct. Surely the contemporaneous written evidence of the trade is a better guide to the state of knowledge.
In my experience, as an apprentice in the 1970's, the shop foreman would have a collection of old reference books that would come out when the combined experience of the shop was beat or struggling to find a solution to a problem.
