6 
ANIMALS IN MOTION. 
demonstrated all the mysteries connected with the various 
gaits of a horse, it was recognized that the work was 
incomplete, in consequence of the difficulty, and sometimes 
impossibility, of obtaining, with wet collodion plates, the 
essential details of rapid muscular action. The results, 
however, excited so much attention in the artistic and 
scientific worlds, that the author was convinced a more 
systematic and comprehensive investigation, with the use 
of the then newly discovered dry-plate process, would 
result in the disclosure of a vast deal of information 
valuable alike to the artist and to the scientist, and of 
interest to the public generally. 
The cost of an investigation on the contemplated 
scale, and the subsequent publication of the results in a 
commensurate manner, assumed such imposing proportions, 
that all publishers to whom the proposition was made 
shrunk—perhaps not unnaturally—from entering a field 
so fraught with possibilities of unremunerative outlay. 
It was under these circumstances that the University 
of Pennsylvania—through the influence of its Provost, 
Dr. William Pepper—with an enlightened exercise of 
its functions as a contributor to human knowledge, in¬ 
structed the author to make, under its auspices, a new 
and comprehensive investigation of animal movements, 
in the broadest signification of the words, and some of 
the trustees and friends of the university constituted 
themselves a committee for the purpose of promoting the 
execution of the work. 
These gentlemen were Dr. William Pepper, Charles 
C. Harrison, Edward H. Coates, Samuel Dickson, 
J. B. Lippincott, and Thomas Hockley. It is with much 
gratification the author acknowledges his indebtedness to 
these gentlemen for the interest they took in his labours, 
for without their generous assistance the work would 
probably never have been undertaken. Among many 
others who also rendered valuable aid in his researches 
were Doctors F. X. Dercum, Geo. F. Barker, Horace 
H. Furness, Horace Jayne, and S. Weir Mitchell, of 
the university; Craige Fippincott, Arthur E. Brown 
(Director of the Zoological Gardens), and Fino F. Rondi- 
nella and Henry Bell, the authors two chief assistants, 
who, respectively, had charge of the electrical and 
developing departments. 
The outdoor labours were recommenced in the spring 
of 1884, and terminated in the autumn of 1885. More 
than a hundred thousand photographic plates were used 
in the preparation of the work for the press. The results 
were published in 1887, with the title of “ Animal 
Focomotion.” The work contains more than 20,000 
figures of moving men, women, children, beasts, and 
birds, in 781 photo-engravings, bound in eleven folio 
volumes. 
The great cost of printing and manufacturing the 
work—independently of the preliminary expenses—neces¬ 
sarily restricted its sale to a comparatively few complete 
copies. 
With a view of supplying the demand of art and of 
science students, and others whom the subject interests, 
it has been decided to select a number of the most 
important plates made at the university, and to republish 
