Patent number 1,593,429 was issued to David William Brunton of Denver Colorado on July 20, 1926, a mere six months after the previous patent issued to Keuffel and Esser. This patent marks the final contribution of David William Brunton to the instrument that bears his name; seventeen months after this patent was issued, David W. Brunton passed away.   This patent covers the addition of the second scale to the clinometer, graduated in Percent Grade.

The thumbnail images above are linked to JPEG images converted directly from the United States Patent and Trademark Office database images.  The original images are available in TIFF format from the USPTO at this link. 

Please be aware that the above linked images are very large. You will probably not be able to see the entire page at once, and will have to scroll the image to see it all.  If you prefer, I will prepare a ZIP archive of all the images and send that to you.