The following text books were in use in 1900. Tantilizingly, some of these books are still obtainable from book collector websites.

Maths
A Treatise on Arithmetic – James Hamblin Smith
Exercises in Algebra – James Hamblin Smith (Later re-published by Hall and Knight).
Euclid – Isaac Todhunter (Euclid was still fashionable to be eventually replaced by general geometry).
Elementary Trigonometry – Hall and Knight
Differential and Integral Calculus -  J. Edwards

Science
The Elements of Statics and Dynamics I & II (Mechanics) – S.L. Loney
Heat for Advanced Students – Edwin Edser
Modern Chemistry (!) – Henry Roscoe

Other
French – Chardenal for Grammar and Sentences. Set books for Cambridge Local.
Latin – Kennedy’s Latin Primer, Caesar to Division III. Gepp’s Latin Prose. Vergil, Ovid and Cicero for Divisions I and II.
English – West’s Grammar. Verity’s Texts for Shakespeare.
History – Ransome.
Geography – Longman’s series for political and physical geography.