In their prime, these well made handsaws were common across the U.S.
Real quality wooden handles with quality steel nuts and bolts to bind the everything together.
Their teeth were designed to be hand sharpened with common files to keep these sharpened for decades even.
Their fatal flaw?
The quality of steel common in manufacturing in those years unfortunately. Galvanizing (zinc plating) would obviously and quickly wear off and leaves the steel itself open to the elements.
Time & humidity ages this exposed steel like people to a degree surprisingly. Oxidization (rust) eats in on all sides and it's why all these saws have a very dark 'finish' or appearence to them nowadays.
Eventually, the fine interior rust makes the steel on the edges more and more 'brittle' relatively speaking. R.I.P., basically.
To sharpen a handsaw, their 'teeth' first need to be re-bent back to the original manufacturer's preferred angles so that the saw will 'bite' properly.
Say hello relatively 'brittle' steel. The classic 'setter' equipment that does this very efficiently on all handsaws is simply too 'forceful' in striking at these individual teeth to bend them back to their original positions.
See the weaken, brittle teeth oddly breaking randomly almost everywhere as the setter machine isn't all that adjustable. The machine is trying to bend real steel so it has to strike real hard one time to get it's job done.
Unfortunately, time is all our enemy here. But in the end, it's just another classic hand tool best put on display for future generatons with all your other grandad's ancient hand tools. Sorry!