Welcome to the forum and you found a good microscope. Bristoline of that vintage were made by Kyowa and they were a very underrated microscope at the time. The optics, especially in the area of contrast were very good for their day and they also had very good mechanical build quality. Kyowa did a lot of stencil badging for U.S. scientific instrument distributors and along with Carton Optical and Meiji are responsible for the bulk of the Japanese made house brands, until the production shifted first to Korea and shortly thereafter to China.
Kyowa, is still in business and they still make microscopes.
You will have a lot of fun with that. They are a nice precise isnstrument.
Thank you for the brief history of the scope, that post made it into my history file I have started for the microscope... It is
built like a precision machine, and I consider myself lucky to have found it at the price I did. Mint condition, not a scratch, or rust spot on it, nice wood carry case, and the optics appear clean, although I may give the whole optical chain a good cleaning. Not to worry, I know how to clean optics-- ground a few mirrors in my "other" hobby, and have taken care of optics for many years. Thanks again!!