The "transitional" period where castings were wedge affairs and
plane retained the concept from woodies gone before.
The evolution of the Slater casting from early wedge tabs to the
sleeker lines of the lever cap.
Two generations of infill planes by Henry Slater of Clerkenwell
Note the heavier casting of the early wedged Slater infill
the thinner lines of the gunmetal lever cap version of later
This one on the left marketed and sold by Tyzack of London,
still selling on the Internet today!