420 THE EMPIRE OF THE AIR. 



Coiitiuiiiug our study of the effects of mass upon fligiit, we shall 

 notice in the tables that as the weights of birds vary between 15 

 grains and 3,5 ounces, the peculiarities of their flight become very dif- 

 ferent. From 3 ounces up to 10 ounces, from 1 pound up to 2 pounds, 

 from 5 pounds up to 10 ijounds, and up to 10 pounds, there are as 

 many steps in the increased economy of power and support in the air. 

 So it seems at least from information furnished by the experts, by the 

 birds. - - - 



It is probable thnt the benetits to be derived from large mass con- 

 tinue to make themselves felt beyond the weights comprised in the 

 tables, and that ui> to some 200 pounds the law remains the same, or, 

 to express it in another way, the curve of variation which may be <'on- 

 structed with the tigures contained in these tables would continue in 

 regular sweei) beyond the points observed. - - - 



When we observe the sailing flight of the Nubian vulture, whose 

 weight varies from 17 to 22 pounds, the one astonishing thing which 

 strikes us immediately is the great steadiness in advancing. When 

 the bird has set his course, accidental wind-gusts do not seem to affect 

 his great mass, which appears insensible to them, and which continues 

 its majestic motion without disturbance. An aeroplane, therefore, 

 w^eighing 200 pounds with its load, ought to move on the wind with 

 even more persistence and regularity than the Nubian vulture. How 

 will it be, then, when from 200 pounds we pass to 1,000 or 2,000 pounds 

 in artificial liight? We may rest well assured that unsteadiness and 

 accidents of the flight, under equal conditions of wind, will diminish in 

 a still greater degree. 



For weights up to 200 pounds, intuition furnishes us with a pretty 

 sound idea of what manner of flight we can get on the wind; we have, 

 as it were, bench marks to refer to; but when we shall come to weights 

 of a ton or so we know scarcely anything, and as for 10 tons, we are in 

 the dark unknown. However, until the contrary be i)roved, T shall 

 believe that the advantages shall continue to grow in the direction of 

 the heavier weights. 



EffecU produeed hy (ifigrcgaiion {in fioels), — Observation seems to 

 show that birds (whether sailing or rowing birds), have mor(^ power 

 to penetrate tlie air when they are congregated in flocks than when fly- 

 ing singly, - - - 



It is a fact well known to sportsmen that a charge of shot so rammed 

 as to scatter does not penetrate as far as when well rammed so as to 

 act as a single b<ill, - - - 



Birds must know this property of aggregated bodies, for they fre- 

 (]uently avail of it. Thus the pas.wrines make no long transits unless 

 grouped in close order, beginning with the sparrows whi(;h have a well 

 fixed order of flight. Pigeons, ducks, geese, swan, cranes, etc., never 

 travel save in serried ranks, in always the same order for the same 

 species. - - • 



