'National' sewing machine?
I recently got some sewing things from my Grandmother and in them was a suitcase with a large black metal sewing machine in it with the name "National" across the body in gold lettering. There's no book, but the machine itself is in excellent condition. The only information I can find online about it is a vintage newspaper ad from the 1950's that has a picture of the machine in it.
Has anyone heard of this brand? Were they industrial machines? Is it something I can use or should I put it away as a keepsake because it may be worth something? I do a lot of heavy sewing, multiple layers of thick fabric and I'd hate to ruin it.
Any help is appreciated, thanks!