How to adjust the speed of an Edison Phonograph

How to set the mandrel shaft to 160 rpm without a strobe. This is shown with a model B 'Home' phonograph, but applies to any machine with the two marks 1-6/10" apart. if your machine does not have the two marks, it would be a simple matter to make marks on a piece of paper 1.60" inches apart and place it on the machine in a convenient place. I want to say thanks again to Kurt Nauck and company for the outstanding job they do conducting the vintage record auctions. They are very conservative in their ratings of records, and I am impressed by the care they take with describing and grading items, and the great care in packing items for shipping.