26o THE STRUCTURE AND LIFE OF BIRDS CHAP. 



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 6J 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 33J 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, 



