260 THE STRUCTURE AND LIFE OF BIRDS cuapP. 
extremity of the humerus, and at the end of the cord 
was placed a scalepan into which small shot was 
poured. The muscle was then stimulated by electric 
currents, and shot was added till the contraction of the 
muscle was exactly counteracted. The weight raised 
was just over 6} lbs. Troy. But in the lever the 
power was much nearer to the fulcrum than the weight, 
and, when this was allowed for, the effort was calcu- 
lated to be equal to just over 332 lbs. Troy. What is 
the value of this experiment ? Does the muscle under , 
the electric stimulus work up to its full power? This is 
very doubtful. Myself I cannot help altogether dis- 
trusting the results. But the muscles of mammals 
have been treated in the same way, and it seems that 
they can develop at least equal energy, 
Experiments might be made with Homer Pigeons 
which would throw much light upon the question. 
They might be weighed in delicate scales both before 
and after a long flight, when the loss of weight would 
help us to estimate the amount of energy put forth, 
though it must be owned that to eliminate all causes 
of error would be extremely difficult. Similar experi- 
ments have often been made with men, their weights 
being accurately taken immediately before and after a 
race, or hard exercise of some kind. The comparison 
of the loss of weight by man and birds in covering 
equal distances would have great interest. It is much 
to be regretted, therefore, that owners of Homer 
Pigeons have as yet made no experiments that might 
supply the necessary facts. The mere opinion that 
the loss of weight is slight is of no value. 
But, however much we may wish for definite evidence, 
