July 6, 1893] 



NA TURE 



223 



•the given year — viz. (A— 1)-4-4, neglecting the remainder. 

 'Add these numbers together, and from the total subtract D = the 

 .number of secular j'ear.=, which were ordinary years (loo, 200, 

 (300, 500, &c.). The sum is then divided by 7, and the remainder 

 I is the day of the week. 



I Example: June 18, 1815. 1815 + 169 + 453-14 = 24234-7. 

 iThe remainder = I. Therefore the day is Sunday. 



This method holds good for any century according to the 

 Gregorian Calendar. Tor the fulian recUoning, the rule is the 

 same, only we must omit the number 15, and write — 2 in its 

 place. The rule is then good without any change for any 

 century. 



Example : Oct. 14, 1066. 1066 + 287 + 266- 2 = 1617+- 7. 

 iThe remainder = o = 7th day, Saturday. C. Braun. 



j Mariaschein, Bohemia, June 15. 



' The Fundamental Axioms of Dynamics. 



M Prof. Lodge (Nature, p. 174) maintains, in opposition to 

 *,jmy correction, that your report of his recent paper on dynamical 

 itixioms was accurate in making the following statement : — 

 jj" Dr. MacGregor objects to the author's definition of energy as 

 i^he name given to "work done,' and contends that this defini- 

 tion assumes conservation." He cites in proof the first two 

 ■ pages of my paper in the February number of the Phil. Mug. 

 These pages, however, contain no reference to this definition, 

 a discussion of his definition of energy as the effect of ■work 

 .:. The definition of energy as a name given to work done 

 discussed on the fourth page, where the following will be 

 fuund : — " In a second version of theaSove argument Newton's 

 ■"•\ law and contact action are the only assumptions made , . . 

 definition of energy in this argument is quite different 

 . that of the earlier paper : — ' Energy is that which a body 

 ^ when it does work ; and it is to be measured as numeri- 

 y equal to the work done.' There is here no reference to 

 ^ing-power. Loss of energy is simply a synonym for work 

 -■ by, and gain of energy for \york done on." 



J. G. MacGregor. 

 jyal .Society, Edinburgh, June 23. 



Artistic Rows of Elms. 



L\ yourNoles.p. 182, June 22, you say that "a correspondent 

 -ires to know where to find any celebrated and artistic hedge- 

 of elms within about thirl y or forty miles of Londoil." 

 he will travel down to Sittingbourne, which is about forty- 

 miles by rail, and five miles less by road, from London, 

 ;an see some fine elms on the south and west bounds of the 

 ■'1 irston Rectory Pastures, locally known as the Park. 



The southern toll of elms is a triple row about 130 paces in 



cngth, the western loll of elms is on Gaze Hill, and is a double 



(Av about 212 paces in length. These elms must have been 



' mted before this century. Being on elevated land they are 



! seen from considerable distances in the neighbourhood. 



;ularly enough they do not belong to the git be. The southern 



however, belongs to the patrons of the living, and the 



;rn toll to my predecessor, the Rev. J. S. Iloare, who 



iiased them, with the land they stand on, from the late 



Twopenny, of Woodstock, Tunstall. I have not yet been 



; to persuade the patrons of the living to purchase them 



1 Jin the present owner. Alex. Freeman. 



Murston Rectory, Sittingbouine, June 27. 



The part of the circle near me was, in the first and second 

 cases, within a few feet of where I sat, the third was over the 

 roof of the verandah, and out of my line of sight. 



Changla Gali, May 25. F. C. Constable. 



Carrier Pigeons. 



Prof. Marey states in his "Animal Mechanism," p. 214, 

 "that a bird which has traversed in a single flight a distance of 

 fifty leagues (which it seems to do without taking any food) 

 weighs only a few grammes less than at its departure." I 

 shall be grateful to any of your readers who will inform me 

 where evidence of this is tO be found. The enormous amount 

 of food consumed by birds would seem to show that the pro- 

 cesses of loss and repair go on in their bodies with great lapidity. 



F. W. Headlby. 



Haileybury College, Hertford, June 27. 



Soaring of Hawk. 



He rest-hourc in which I now am stands close to the edge of 



ecipitous descent. There is a covered verandah in front, and 



ire nearly 9000 feet above the sea. I have just seen a hawk, 



vulture hawk, circle round three times over the precipice. 



: whole time its wings were motionless (to the sight). Its 



circle was on a level with me, the second was higher, the 



I was unquestionably higher still. As I sat I could see 



h the complete first and second circles. To see the last I 



liuuld have had to go to the edge of the verandah. This ap- 



"■ars to be a clear case of rising circles wiihout (apparent) 



"ion of tl e win^s. I have seen the same thing from the 



ns, but have not been so sure of the fact observed. There 



o a light wind blowing, scarcely moving the trees. 



(NO, 1236, VOL. 48] 



A Method of obtaining Glochidia. 



The Glochidia of Anodon are not always easy to obtain. 

 They appear to be retained, and shed only when fish are swim- 

 ming near. 



Tadpoles have the same influence as fish, and a good supply 

 of Glochida may be obtained by examining the tails of tadpoles 

 swimming in a dish in which a few Anodons have been placed. 



G. P. Darnell-Smith. 



60, St. Michael's Hill, Bristol, June 26. 



A NEW STATUE OF ARAGO. 



IN this country the prevailing opinion is that the works 

 of a man of science furnish the best inonument to his 

 memory. Though soinething can be said in favour of 

 that principle, the restriction of its application to 

 students and interpreters of nature is by no means justi- 

 fiable. But a " look around" at the statues, and tablets, 

 and other maiks of public appreciation, shows that a 

 man's greatness is, in general, not measured by his scien- 

 tific labours. They do these things better in France. 

 Those who honour a man and his works desire to proclaim 

 his fame in the market-place, so that all may know that 

 he was a giant among men. Passers-by are thus brought 

 to a knowledge of deeds that they wot not of, and they 

 see that a life devoted to science is one to be emulated. 

 Thoughts of this kind forced themselves upon us when 

 it was announced a few vv-eeks ago that a statue to Arago 

 had been unveiled in Paris. 



Fourteen years ago a statue to Arago was erected 

 at Perpignan, near his birthplace, and in 1886 it 

 was decided to commemorate the centenary of his 

 birth by raising the funds for erecting a statue at Paris. 

 A committee, having the late Admiral Mouchez for 

 its president, was then formed, and an appeal for subscrip- 

 tions was made. Thanks to the contributions from the 

 State and the Municipal Council of Paris, the neces- 

 sary money was soon raised, and M. Oliva was com- 

 missioned as the sculptor. The statue has been completed 

 for some tiine, and it would have been unveiled last 

 summer but for the death of the artist, and later, of 

 Admiral Mouchez, who was the prime mover in the 

 matter. 



The inauguration of the statue at the back of the Paris 

 Observatory took place under M. Poincarc, Minister of 

 Public Instruction, on June 11. Among those present 

 were M. E. Arago, French Ambassador at Berne, and son 

 of the renowned astronomer ; M. Tisserand, the director 

 of the Paris Observatory; M. Cornu, M. Huet, repre- 

 senting the Prefect of the Seine; and M. Muzet, vice- 

 president of the Municipal Council of Paris. Each 

 of these gentlemen dwelt in eulogistic terms on the 

 career of Arago as a public man as well as a man of 

 science. " Arago introduced physics into astronomy," 



