palmers pocket scale

I have been given a book from my Aunt titled, Palmer's Pocket Scale. It seems to be a canvass type cover with embossment on the front and back. Inside the first page:
Boston
Published by Aaron Palmer
D. H. Ela, Printer, 37 Cornhill
1845

48 pages with a circular cardboard measurement wheel inside the back cover.
Could anyone tell me anything about this as I cant't seem to be able to pull anything up on the internet. Also, the value if you know it.
Thank you in advance
Sharon