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APPENDIX. VI. 
lesson, he is said to sing his song round, or in 
all its varieties of passages, which he connects 
together, and executes without a pause. 
I would therefore define a bird’s song to be 
a succession of three or more different notes, 
which are continued without interruption dur- 
ing the same interval with a musical bar of 
four crotchets in an adagio movement, or whilst 
a pendulum swings four seconds. 
By the first requisite in this definition, I 
mean to exclude the call of a cuckow, or 
clucking of a hen,* as they consist of only two 
notes; whilst the short bursts of singing birds, 
contending with each other (called jerks by 
the bird-catchers) are equally distinguished 
from what I term song, by their not continuing 
for four seconds. 
As the notes of a cuckow and hen, therefore, 
though they exceed what I have defined the call 
of a bird to be, do not amount to its song, I 
will, for this reason, take the liberty of terming 
such a succession of two notes as we hear in 
these birds, the varied call. 
Having thus settled the meaning of certain 
words, which I shall be obliged to make use of, 
* The common hen, when she lays, repeats the same note 
very often, and concludes with the sixth above, which she holds) 
for a longer time. 
