ro 
ANIMALS 
the intention of the artist as he himself uses in the execu¬ 
tion of his work. 
The art of expressing ideas, or conveying information 
by pictorial representation, naturally long preceded the 
invention of letters ; these etchings and carvings of animals 
by primitive man were apparently executed for no other 
purpose than to gratify his artistic impulses, or to record an 
event for which the language of his time was inadequate. 
The importance of a correct knowledge of the various 
functions of the limbs in locomotion was recognized in 
the early ages of Greece. Aristotle devoted much atten¬ 
tion to the subject, and Xenophon, Pliny, Vegetius, 
and many other writers of ancient times tell us of the 
great interest manifested by their respective contemporaries 
in the training and employments of the horse. 
None of these distinguished authors, however, have 
left us any information as to the manner in which the 
various movements they write about were executed. 
No investigation—worthy of the name—is known to 
have been made until the middle of the seventeenth 
century. 
In 1680 Borelli of Naples published his “ De Motu 
Animalium.” This celebrated mathematician evidently 
conducted his experiments with great care; but, although 
he disapproved of the generally accepted idea of the walk, 
he allowed the Egyptian interpretation of the gallop to 
pass unchallenged. 
In 1658 the Marquis of Newcastle published at Ant¬ 
werp his elaborate and well-known work on “ Horseman¬ 
ship.” The original was in the French language. A com¬ 
MOTION. 
plete English edition was issued in 1743. The two folio 
volumes were illustrated with many finely executed copper¬ 
plate engravings of horses performing various feats of 
motion, and a chapter was devoted to “ The Movements 
of a Horse in all his Natural Paces.” 
As these analyses were the sources from which all 
lexicographers—English, French, and German—from the 
date of publication to the end of the last decade, seem 
to have taken their definitions of the various gaits of a 
horse, they are included in an appendix to this volume. 
In the early part of this century, Ernst and Wilhelm 
Weber, the former an eminent physiologist, the latter 
an equally distinguished physicist, published at Leipzig 
the results of many years’ patient devotion to the subject. 
The researches of Dr. E. J. Marey, of the College of 
France, and Dr. J. Bell Pettigrew, of the University of 
St. Andrews, are of too recent date, and are too well 
known, to require more than a passing allusion. The 
former w r as the first to avail himself of scientific appli¬ 
ances to automatically register the characteristics of move¬ 
ments. This was done by an ingenious apparatus, carried 
by the rider of an animal, which caused styles—actuated 
by pneumatic pressure—to leave a record on a revolving 
cylinder. 
Although the actinic qualities of light, when its rays 
were directed to organic matter which had been treated 
with certain chemicals—especially salts of silver—was 
well known to the alchemists of the Middle Ages, and 
is now in universal use as a method of picture-making; 
it was only about a quarter of a century ago that its value 
