I sold several of these 20" "SIMONDS SAW WORKS"  blades a while back here on ebay. When I first listed one, I received a very informative email from a gentleman who's relative (grandfather?) who represented Simonds tools  many years ago....... He noted the "The SIMONDS SAW WORKS" name had stopped being used in 1918,  there after it was called the Simonds Saw Company (or something similar) the point being the "Works" was no longer in the title after 1918. Also I believe Simonds moved to a different manufacturing location/city at that time. So, I'm told this saw blade is from around 1918 or earlier

As you can see it is very dirty with a hundred years of protective grease and collected grime. Most of it cleans up as shown with some solvent cleaner BUT the are some visible and hidden spots with some rust in places so look at our picture closely

Six of these blades came to me in 1979 with a large cut off saw that worked exactly like the Bosch GCM12SD sliding miter saw...only mine was very old and weighed about 2000 pounds. I called it a broken arm saw because it had one vertical and one horizontal arm that hinged open and closed together in unison to locate the saw motor and it's blade....with zero friction...........At 3600RPMs it screamed so I bought a 16"  carbide blade for it and it still screamed

 Some people make these into shop clocks.........