070 Becentli/ publislied Ornithuloglcul M^orks. 



the body^ so far as it is heavier than air. Experiments have 

 to be made by aeronauts as to what pace, what surface area, 

 and what curve of the wings gives the best results for their 

 machines ; but with a bird the case is different, as it can 

 change its position without fear of a fall, can suit the 

 curvature of its wings to vai'ying circumstances, and can 

 allow the air to pass through its wing-feathers and so reduce 

 the pressure at any given moment. The air too can uplitt 

 the tips of the primaries of its own accord. 



The bird in fact loses and regains its equilibiium, but the 

 flying man must never lose it. Birds have various ways of 

 righting themselves, by making a more powerful stroke with 

 one wing than the other, by inclining the body, by uplifting 

 tlie wings, or by using their legs and tails. When INIr.Headley, 

 however, instances a skater's turn of the head without loss 

 of equilibrium, he might have stated that the head and 

 shoulders of the skater are used to alter his direction and 

 change his edge; similarly the hird by a turn of the bend 

 need not lose its equilibrium, it is true, but may also wish to 

 suddenly alter its course. 



After a study of the laws of flight and so forth, the author 

 discusses motive power in a bird, the bones and muscles 

 utilized, the structure of feathers, and all that is necessary 

 to a full understanding of the matter. Here he has little that 

 is new to tell us that may not be learned in anatomical or 

 other text-books, but, as a summary, his pages will be found 

 of the greatest use to those not versed in the subject. 



The final chapters on varieties of wing and flight, on pace 

 and lasting power, and on the eftect of the wind, will perhaps 

 be to some as interesting as any in the book, including as they 

 do the much vexed question of the rate at which birds can fly, 

 on migration and at ordinary times. 



96. Horshrufjh mid Davies on South- African Game-birds. 



[The Game-birds aud Water- fowl of South Africa. By Major Boyd 

 Horsbrugh, with coloured plates by Sergeant C. G. Davies, I'art 1. 

 Witherby & Co., March 1912.] 



This is a very pleasing book. The drawings of Sergeant 

 Davies are capital, while the letterpress, by the well-known 



