232 



SCIENCE. 



[Vol. IX., No. 214 



denying this he seems to me to reduce the force ex- 

 erted hy the train on the locomotive to the qtiantity 

 R alone ; and since R is less than F, the pull exerted 

 hy the locomotiTe on the train, he thus abandons the 

 doctrine that "all force is of the nature of stress," 

 and that ' ' the stress is measured numerically by the 

 force exerted on either of the two portions of mat- 

 ter." 



The quotation which Professor MacGregor makes 

 from Poisson I shall not attempt to discuss at length ; 

 for I am not familiar with his writings, and do not 

 know exactly what meaning he attached to the word 

 resistance. If he used this word as I understand 

 Professor MacGregor to use it, to indicate an oppos- 

 ing force, and if he was at the same time committed, 

 as I understand Professor MacGregor to be, to the 

 yiew that one force always implies an equal and op- 

 posite force, then I can only say that I think Poisson 

 was wrong in one part or the other of his doctrine. 



E. H. Hall. 

 Cambridge, March 5. 



Comparative taxation. 



WhiJe I cordially accept all Mr. Henry B. Gard- 

 ner's statements in regard to the insufficiency of my 

 study of the comparative taxation in Europe and 

 America, I cannot accept his conclusions. He says, 

 in fact, " The inadequate scope of the work has in 

 large measiire destroyed the value of the study." To 

 this I cannot agree ; and my witness is Mr. Gardner 

 himself. My Avork has brought out his intelligent 

 criticism, and has turned the attention of himself 

 and of very many other persons to the importance of 

 developing the science of comparative statistics, 

 which is what I have aimed at. 



It is very true that I have not attempted to com- 

 pare the relative taxation of cities, towns, and other 

 subdivisions of states in Europe with those of Ameri- 

 ca; it is very true that some of the cities of this 

 country are excessively taxed as compared to those 

 of Europe : all the more reason for a complete study 

 of the subject. Where are the materials for such 

 an investigation ? I have given, to the best of my 

 ability, the relative biirden of national taxation. I 

 stated that this part of the taxation of countries 

 should be considered separately from that of the 

 towns and cities, for the reason that in Europe a 

 very large part of the national taxation is expended 

 for destructive purposes or for the support of privi- 

 leged classes ; while, with the exception of a few cities 

 in this country, the revenues derived from local 

 taxation are paid out for constructive purposes both 

 there and here ; and on the whole, in spite of the 

 cumbersome nature of the collective work of cities, 

 counties, and towns, the people of this country get 

 about seventy-five cents' worth on a dollar for what 

 they pay in municipal taxes. 



Moreover, although Mr. Gardner may not be able 

 to find exact returns of taxation in European coun- 

 tries corresponding to the per capita figures which I 

 have submitted, yet I claim to have proved them after 

 as complete examination as is open to a private and 

 unofficial person who does not read German. I hold 

 that the revenue of state forests, mines, and other in- 

 strumentalities of subsistence which are often con- 

 trolled in Europe by governments, constitute as true 

 a tax upon the people as if they had been assessed di- 

 rectly upon their property ; and I am of opinion that I 

 have understated the burden of national taxation in 



Europe rather than overstated it. Suffice it that the 

 figures have attracted attention ; and it may be that 

 within one, two, or three years a complete compari- 

 son of national as well as state, county, and town 

 taxation may become possible. I should be glad to 

 see Mr. Gardner try his hand, not so much in criti- 

 cising my work, as in preparing more accurate and 

 more complete tables. Edwaed Atkinson. 



Boston, Marcli 5. 



On the flight of birds. 



The wing is extended upward from the horizontal 

 position by the deltoid and the latissimus dorsi 

 muscles to a line which is perpendicular to the body, 

 and is quickly again depressed to the horizontal 

 position by the pectorales. This constitutes the 

 first stage of the ' stroke.' ' Recover ' is initiated by 

 an inward rotation of the humerus, semiflexion of 

 the wing at the elbow (the pinion remaining ex- 

 tended and directed obliquely downward and out- 

 ward), and is carried well forward to a degree suffi- 

 cient, when seen in profile, to conceal the head. In 

 this position the primaries are semirotated so as to 

 present the least amount of surface to the air in the 

 direction in which the bird is moving. The impetus 

 excited by the stroke carries the bird upward and 

 forward. In the second stage of ' recover,' the hu- 

 merus is rotated outward, the arm is quickly raised, 

 the primaries restored to the position seen in the bird 

 at rest, and the wing is a second time in the position 

 for the ' stroke.' In the eagle and the hawk the legs 

 are in the position of the 'stroke' when the wings 

 are similarly placed. During the ' stroke ' the legs 

 move backward. This motion continues during the 

 ' recover ' of the wing, so that the time of the ' re- 

 cover ' of the wing is also that of the ' recover ' of 

 the leg. The action of both wings and feet, since 

 both pairs act together, is what I propose to call 

 ' synadelphic' 



The study of the flight was confined to the eagle, 

 the hawk, the pigeon, and the parrot, in the series 

 of instantaneous photogz-aphs taken by Mr. Edward 

 Muybridge, under the auspices of the University of 

 Pennsylvania. Harbison Allen. 



Philadelphia, March 7. 



On the serpentine of Syracuse, N.Y. 



An especial interest attaches to this rock for two 

 reasons : 1°, because of the almost total absence of 

 rocks of this class, or indeed of any intrusive rocks, 

 from the undisturbed paleozoic strata of New York ; 

 and, 2", because of the importance vv^hich has been 

 recently attributed to it by Dr. T. Sterry Hunt, as 

 affording evidence in favor of his chemical precipita- 

 tion theory of the origin of serpentine. 



The Syracuse serpentine was discovered in 1837, 

 and was described by Vanuxem in his third annual re- 

 port in 1839 (pp. 260 and 283), and in his final report 

 on the geology of the third district in 1842 (p. 109). 

 It is also mentioned by Beck, in his ' Mineralogy of 

 New York.' as a ' dike or bed ' (1842, p. 275). Dr. 

 Hunt published an analysis of this rock in the Ameri- 

 can journal of science for 1858 (xxvi. p. 236), and 

 has laid great stress upon it in his recent essay on 

 the geological history of serpentines. 



Through the courtesy of Prof. A. H. Chester of 

 Hamilton college, the writer has been enabled to 

 study a very complete suite of this rock and its asso- 

 ciates, which was collected by the late Prof. Oren 



J 



