I must assume that these planes were used to help form the round cross section of Masts for ships, as the name implies! At various stages they appear in the catalogues under ‘Sundries’; ‘Mast and Fork Shaft Planes‘ and ‘Mast and Spar Planes‘. A Fork Shaft plane was a similar plane to a Mast Plane but was used for rounding handles and similar work and was a single iron plane.
The first reference I can find is in 1897, so we can assume that the planes may have been introduced a couple of years before then.
In 1909 they are re-numbered and listed thus:
We see this [below] in 1921, but I would have assumed that there would have been a price increase after WW1. So from 1897 to 1921 there was no price increase! Amazing social stability.
In 1928 we are, for the first time, shown a drawing of the plane. I do note that the planes now are called ‘Mast or Spar Planes‘ :
The last catalogue entry for these planes appears in the 1938 Catalogue and it may be safe to assume that they were dropped from manufacture c.1940. The entry is exactly the same as in 1928.
The picture below shows that the Mast Planes had a hand written label on the box, this one being 1.3/4″.
I believe that the stated size was the radius of the circle that it could produce.
The one below is a 2.1/4″ size, the largest produced.