Characteristic Studies  is H. L. Clarke's paralell to the Arban Characteristic Studies.

Here is the Clarke's introduction text:
 

INTRODUCTION

Ever since J. B. Arban demonstrated the musical and artistic possibilities of the Cornet, while concertizing in France, Germany and England, as long as 1848, this instrument has remained one of the most popular throughout the world for solo playing. Others of equal renown, with whom he vied, were the great French Cornetist and Author, Saint Jacome, Levy and Arbuckle from England, and later on, Liberati, Emerson and a host of celebrated American soloists of the past and present.
In view of the progressive demands of modern Cornet playing, I made a thorough study of violin methods and exercises, and adapting much of' the material I found therein, f or the needs of Cornet players. As a practical result the Twentyfour Characteristic Studies contained in this book, while of difficult grade, have been adapted from existing violin studies, in carefully arranged form to suit the requirements of the Cornet. They have been provided with metronomic tempo indications, proper breathing marks and will aid the student to gain absolute control of technic, articulation, slurring and endurance.
Cornet students should not exert or torture themselves, by trying to master all these studies before careful preparation. With well developed and proper embouchure, they will offer no undue difficulties. My Technical Studies, Series Two, if practised carefully as per instructions, will help the student to play with comfort and ease.
Cornet players should strive to become creative, and not imitative by persistently copying some great soloist. To the contrary, they should endeavor to produce original ideas which no other players have ever thought of, and try to demonstrate their own musical and artistic individuality. The following studies and solos should assist in arousing ambition and perseverance amongst all serious minded students, and as everyone has an equal chance in gaining fame, I sincerely hope that this work will prove both helpful and beneficial.

REMARKS ON TONGUING

This is a subject which has caused more controversy than any other pertaining to the Cornet, and is one of the most important factors of correct cornet playing.
Perhaps very few players have ever considered that different languages have an effect on the tongue.
Being personally acquainted with many celebrated artists throughout the World and conversing with them on the different points of cornet playing, I have noticed that nearly all tongue in a different way. Some tongue heavily, others lightly, but those of the Latin Race as a whole, seem to have the hest control over proper attack, whether for Single, Double, or Triple Tonguing. Perhaps they give more study to this particular point; then again their language may help them to be more decisive, besides guiding them with great certainty as to the attack for the different varieties of tonguing, which should be taken up as soon as a pure tone is acquired.
Many players advocate certain syllables to he used in proper tonguing, such as "Te," "Ta," "Tu," "Tit," etc. This places the ambitious student in doubt, wondering which syllable he should adapt.
The attack should be started as distinctly as possible and must be positive. But there is a difference in using the tongue when playing loud or soft, also when playing either high or low registers. When playing loud, more of the tongue is used and less when playing softly. The tongue should work perfectly with the muscles of the lips, contracting it slightly for the higher notes, and relaxing it for the lower notes.
My own method of tonguing is rather unique. But the results I have accomplished by diligent study and practice, have proven to me to be not only the easiest, but the most practical in many ways, both for solo and other work.
First, always practice softly, try to produce a light positive attack in the middle register. My tongue is never rigid when playing, and rests at the bottom of my mouth, the end pressed slightly against the lower teeth. I then produce the staccato, by the center of the tongue striking against the roof of the mouth. This I have practiced so as to acquire a rapid single tonguing without fatigue, nor causing a clumsy tone, and when under full control, Double and Triple Tonguing become a simple matter by diligent practice, keeping the mind upon each articulation.
To produce a sforzando attack, such as in Trumpet playing, the point of the tongue is used decisively. In my Elementary Studies, First Series, I state that there is no set rule for cornet playing, except by playing naturally; consequently there is no set rule for tonguing. Each player must discover the most natural and easiest way for himself. There is any amount of experimenting necessary, before one really feels the proper way. Use of the syllable "Tu," not "Thu" in the middle register, seems to be the most natural way to express the attack.
As a matter of argument, when the muscles of the lips are contracted for high tones, one would  necessarily pronounce "Te," and when relaxed for low tones, "Tu"; consequently it would be unnatural, and almost impossible to use the same syllable for tones in all registers on the cornet.

The book is published by Carl Fischer (Third Series 02281)
Copyright 1915 by Herbert L. Clarke