1865.] Dr. Davy on the Temperature, fyc., of Birds. 453 



The results given in the preceding Table may justify the remark, aeon- 

 elusion that might be anticipated, that generally the comparative weight of 

 the bones of each species of birds bears a relation to the power exercised 

 by the limbs on parts to which they belong ; of this striking examples are 

 afforded in the instances of the upper and lower extremities of the buzzard 

 and common fowl ; of the one, the buzzard, a bird of powerful flight, the 

 wing-bones are proportionally the heaviest ; whilst of the other, the fowl, 

 which makes so little use of its wings and so much use of its legs, the 

 opposite is the case ; and other contrasts not less striking are noticeable. 



Also, as might be anticipated, and in accordance with what was before 

 observed of the feathers, the primates of each wing, the weight of the bones 

 of each was found to be nearly the same, the difference being no greater 

 than might be expected from the mode of preparing them. 



4th. Of the Composition of some of the principal bones. This was 

 ascertained by calcination, by which merely the proportion of animal or 

 combustible matter was determined and that of the incombustible, chiefly 

 phosphate of lime. I shall first give the results of the trials on humeri 

 and femora : in each instance the shafts of these bones were selected ; and 

 previously to a thorough drying over steam, they were deprived of their 

 investing membrane internally as well as externally. Though the quantities 

 employed did not exceed a few grains, and were even less than a grain from 

 some of the smaller birds, yet as the weighing was carefully made to the 

 one hundredth of a grain, the results may be received as tolerably reliable 

 for comparison. 



If inferences may be drawn from these results, they seem to favour the 

 conclusion, first, that the proportion of phosphate of lime is somewhat greater 

 in the bones of birds, the cylindrical of the extremities, than in the like 

 bones of the Mammalia ; and secondly, that the composition of those con- 

 taining air and of those containing marrow is much the same, which is not 



