HIS WORK AS CONSERVATOR OF MUSEUM 63 
Knox; and thus began the fourth period of his life, 
which extended to 1841. 
The amount of work accomplished by him 
during that period, with all the care and perfection 
so characteristic of him, was marvellous, while on 
the 1 esults of it and of the many years of previous 
preparation his fame as an ornithologist mainly 
rests. 
In the preface to the Rapacious Birds , Mac- 
Gillivray gives the following reasons for publishing 
that work at the time he did—1836 
I have, he writes, “ shot, examined, described, 
and depicted a very considerable number of our 
native birds. With what success my efforts have 
been crowned you may have an opportunity of 
judging some years hence. But as the period at 
which I propose to introduce to your notice my 
great work, as I may call it, is far distant, I have 
thought that you might not be displeased to 
receive an account of some of our feathered tribes 
even if very imperfect, provided it should convey 
information not elsewhere to be obtained.” 
He then goes on to explain that the principles 
of classification of birds adopted by all con¬ 
temporary ornithologists are defective, as being 
confined to the consideration of certain external 
oigans only, such as the bill, the feathers, the 
claws, etc., and he proceeds:— 
“But as the exterior alone of birds has hitherto 
occupied the attention of ornithologists in this 
country, and, indeed, in almost every country I am 
unwilling to frighten away the student ’by a 
