"Private" wrote

I note that Robertson was having the same kind of legal problems
protecting his invention as the Wrights were having at the same time.
Today we realize that he would perhaps have been smarter to give away the
license to use the screws and to retain the license for the drivers.

It may be of interest that square drive screws are becoming much more
popular in construction work.

I have used square drive finish screws. Neatest thing since sliced bread,
where it is needed, as in having a 12d finish nail sized hole, but the
ability to pull something together, and hold much better than a nail.

Also, deck screws with a square drive are around. It may be that if there
is still a royalty for using Robertson screws, they got around it in an
innovative way. These screws I am talking about can be driven by a Phillips
head driver (very poorly, though) but have the inside of the Phillips slots
enlarged so that a square drive will fit in it. If you keep a reasonable
amount of pressure on them, they WILL not slip.

I look forward to seeing more and different kinds of hardware showing up
with square drives. I'll switch every one out that I can find!
--
Jim in NC