Renowned for his talents as organist and composer, Charles-Marie Widor (1844–1937) was also a professor at the Paris Conservatoire, where his vast knowledge of counterpoint, fugue, and orchestration benefited such students as Honegger, Varèse, Milhaud, and Dupré. In the course of his four decades of teaching at the Conservatoire, he wrote this study of instrumentation, The Technique of the Modern Orchestra, which he viewed as a supplement to Berlioz’s celebrated but dated treatise on the same subject. Full of insights and details not found in other manuals of instrumentation, Widor’s 1904 text presents a comprehensive catalog of the various abilities and qualities of all the orchestral instruments. It also features an abundance of practical advice regarding instrumental combinations and relevant works to study. This classic work represents an invaluable reference for any student of orchestration.
It's nice having access to outdated reference books...encyclopedias and dictionaries for example, so one can see how things have evolved. Not only is the information different--they have different character, too.
This book is quaint in many ways: musical instruments have changed, musical notation and music itself has evolved/devolved, of course; but what really makes this book charming is Widor's attention to detail. He shows which "shakes" (tremolos) work on a given instrument, and which ones don't. And he includes useful excerpts of countless musical compositions.
Finally, Widor doesn't attempt to hide his prejudices. I don't know why that doesn't surprise me--his Toccata from Symphony No. 5 for organ indicates he wasn't a shrinking man. He describes the Cor Anglais as having a "very powerful lower register", the upper "weak and sickly." The cornet requires "less talent and artistic intelligence" than the trumpet. French horn bass clef notation "triumph of absurdity."
And...I use this as my main reference for musical arranging all the time! I'm outdated, too.