POPULAR MISCELLANY. 



427 



rains. The object of exposing the bodies 

 in this way is said to be to avoid pollut- 

 ing the earth by burying them. Through- 

 out the Zoroastrian writings that remain, 

 this principle is continually dwelt upon. 

 Cremation is even a greater crime than in- 

 terment of the dead, because, it was alleged, 

 of the exceeding holiness and purity of fire, 

 which must not be polluted. These views, 

 it has been suggested, originated in the ab- 

 horrence of primitive Zoroastrianism for 

 cannibalism and human sacrifices, on ac- 

 count of which it surrounded the dead hu- 

 man body with such awful horrors and ob- 

 servances as should effectually defend it 

 against them. 



The Flying Force of Birds. Dr. Karl 

 Miillenhoff has published, in the proceedings 

 of the German Society for the Advancement 

 of Aeronautics, a paper on the force exerted 

 by birds in flying. The latest calculations, 

 by Marey and others, give the maximum 

 force exerted by birds at 1*2 to 1"4 kilo- 

 gramme per square centimetre of muscular 

 section numbers that are not greater, but 

 rather less, than those which represent the 

 strength of other animals. Dr. Miillenhoff 

 deduces from his own calculations that the 

 labor performed by the wing in any time- 

 unit is little if any greater than that in- 

 volved in walking on the ground. This re- 

 sult agrees with the facts shown by experi- 

 ments that the weight of doves was not 

 changed after considerable test-flights ; and 

 that it fell off only a few grammes after a 

 flight of three or four hundred kilometres. 

 Quite different from this are the results 

 afforded by the experience, say, of veloci- 

 pedists ; one of whom confessed to the au- 

 thor that he had lost ten pounds after a 

 few months of cycling, and who suffered 

 after an hour or so of his exercise from a 

 greatly quickened pulse and an intense 

 heart-beating. Prechtl, of Vienna, some 

 years ago published the conclusion that the 

 force exerted by birds in changing their 

 place was not greater than that of the other 

 animals, and that the amount of force ex- 

 erted by large and small birds was rela- 

 tively the same. Helmholtz, twenty-seven 

 years later, came to an opposite conclusion 

 which he based, however, only on theoreti- 

 cal grounds. He predicated a geometrical 



similarity in the forms and movements of 

 smaller and larger animals, and that a great- 

 er increase in power must be given the 

 larger animals to overcome the greater re- 

 sistance they have to encounter. Dr. Miil- 

 lenhoff having subjected this theory to an 

 experimental test, has found it not sound. 

 The geometrical similarity of motions does 

 not exist. While the wings of the larger 

 birds move up and down, those of the 

 smaller birds move diagonally, and of the 

 smallest nearly horizontally. The author 

 having also examined the rate of increase 

 of velocity corresponding with increase of 

 size, separately as regards vertical and hor- 

 izontal movements, finds that increase in 

 the weight of' the body is not accompanied 

 by increase in the relative muscular mass ; 

 that the amount of absolute force does not 

 increase as the bird becomes larger; that 

 no differences are apparent between birds 

 of different sizes in the velocities of the 

 muscular contractions; and that, regarding 

 differences in the quantity and quality of 

 the food consumed by the larger and smaller 

 \ birds concerning which there is question 

 I while the labor performed in flight can be 

 furnished only at the expense of a corre- 

 sponding consumption of chemical elasticity, 

 j we can so far not make any definite decla- 

 ration concerning either the amount of 

 substance consumed in flight-work, or the 

 amount of food required to compensate for 

 the substance that is consumed. 



The Problem of the Irrawaddy. Mr. 



Robert Gordon, who has recently addressed 

 the Royal Geographical Society in support of 

 his theory that the Irrawaddy is the outlet of 

 the Sanpo of Thibet, says that that river 

 presents the greatest geographical problem 

 in Asia. Mr. Gordon's view is contradict- 

 ory of the opinion generally held by geog- 

 raphers that the Sanpo is the Brahmapoo- 

 tra, a river that it must meet or run around 

 before it can reach the Irrawaddy. In favor 

 of his theory, he adduces the testimony of a 

 number of Thibetan and Chinese authorities, 

 dating from times of considerable antiquity ; 

 the size of the Irrawaddy in its upper course, 

 which can not be supplied by the few small 

 streams and the limited water-shed the geog- 

 raphers give it ; the testimony of the names 

 of various rivers and branches of rivers in 



