Stanley No. 55 screwdrivers

I love the bolster heads on these tools, turned down as concentric circles of smaller diameters.

I suspect that this is part of the 1932 U.S. Patent No. 1839835 issued to Harris J. Cook of New Britain, Connecticut.  Cook assigned the patent to the Stanley Works, and the patent appears on an earlier screwdriver in my possession:

The letters of patent explains that.  "The head 13, which may be of any suitable configuration, is preferably tapered down so as to merge into the shank."  It would appear that on later screwdrivers, Stanley improved the appearance of the screwdriver by adding more stepped rings.  Who'd bother to do that today?  I also like the fact that a model number is stamped on the tool:  "Igor, bring me the Stanley No. 55, stat!"