Omar Khayyám (1048-1131 A.D.) was a Persian mathematician, astronomer, philosopher, and poet. He also wrote treatises on mechanics, geography, mineralogy and music. While it is not clear from the diary which of Omar Khayyám’s writings had engaged Arthur Linfoot’s interest, it was almost certainly his most famous work, The Rubáiyát.
The image here is of Arthur Linfoot’s own copy, which is still held in a family collection and is clearly marked “second edition”.
Arthur Linfoot wrote that he had “read a bit of Omar Khayyam” while on holiday in St. Andrews on 29 June 1915.