Help with Morrill saw set

[dm65]

Got a nice saw set today (another 'tinterbay bargain)

Obvious how to use, with a wheel that should be set to match number of teeth I assume

There is another thumbwheel underneath though that looks like it is used for what ? clamping the blade is surely all it can do but that would be a pain locking for each tooth (see below)

Does anyone use one of these ?

 

[dunbarhamlin]

Try this from Toolemera: http://toolemera.com/catpdf/morillCat1917.pdf

 

[dm65]

Cheers dunbarhamlin - nice to see the original brochure

So its a gauge, but I can't see what its for - is it just for keeping the anvil close to the teeth or is it used to keep the tool at the correct angle to the saw blade ?

Tried a practice run and it seems to hinder moving along the blade