All of the (not very many) weights I have seen with the "Ysart Bros" signature have had a similar "chunky" look to them and all have had a basic concentric pattern.
I included an image of this type of signature in a PCC Newsletter article some time ago. Or maybe it was an article that Derek wrote and for which I provided some images. Can't remember right now.
Probably all of the "Ysart Bros" text was applied by hand using a brush or simialr implement! I have seen "Ysart Bros" on its own as well as with "Handmade in Scotland" and those lines can appear with the "Ysart Bros" at the top or the bottom (around the ground out base section).
See the Ysart Glass website for more info.