Definition of "unprejudiced"

On becoming a member of the College of Physicians, I made a tour of the principal cities of Europe, taking letters of introduction to eminent medical men; and gathering from many theories and modes of treatment, hints to enlarge the foundations of unprejudiced and comprehensive practice, I had resolved to fix my ultimate residence in London.

1861 September 28 – 1862 March 8, [Edward Bulwer-Lytton], chapter I, in A Strange Story. […], volume I, London: Sampson Low, Son, & Co., […], published 1862, page 1

But when it comes to capacity on the road, no unprejudiced observer can deny that Mr. Bulleid produced in these engines two designs that are capable of almost anything, whether in speed or load haulage.

1951 April, Cecil J. Allen, “British Locomotive Practice and Performance, 1939-1951”, in Railway Magazine, number 600, page 267