August i6, 1900] 



NATURE 



Z77 



{Ckelydra serpeiifina) from North America, a Leopard Tortoise 

 [Testudo pardalis) from South America, two Argentine Tor- 

 toises {Testudo argentina) from the Argentine Republic, de- 

 posited ; a Gold Pheasant ( Thaumalea picta, <J ) from China, two 

 Little Bitterns (Ardet/a minuta), European, purchased ; a 

 Burrhel Wild Sheep (Ovis burrhel), born in the Gardens. 



OUR ASTRONOMICAL COLUMN 



Comet Borreli.y-Brooks (1900 3).— The following elements 

 • 1 ephemeris are furnished by Herr J. Mdller in the Astrono- 

 che Nachrichten (Bd. 153, No. 3654V 



Eletnents. 

 T=i900 Aug. 3'298 Berlin Mean Time. 



« = 12 30*2 1 

 a =328 18 j- 1900-0 

 /= 62 35-6] 

 log f/= 0-00636 



Ephemeris for 12/1. Berlin Mean Time. 



Aug. 



Ephemerls for Observations ok Eros.— The following is 

 a continuation of co-ordinates computed by Ilerr F. Ristenpart 

 {Astronomische Nachrichten, Bd. 152, No. 3643). 



Ephemeris for izh. Berlin Mean Time. 

 1900. R.A. Decl. 



The Astrographic Chart Conference.— The fourth 

 meeting of the International Committee for directing the photo- 

 graphic delineation of the sky has recently been held in Paris, 

 commencing July 19. The first jmatter taken in hand was the 

 appointment of a sub committee of nine astronomers to draw up 

 a scheme for the systematic observation of Eros during the 

 coming opposition, for determinations of solar parallax. The 

 reports from the co-operating observatories show that in fifteen 

 of them the work is being vigorously pushed forward ; unfor- 

 tunately, in the remaining three, Rio de Janeiro, La Plata and 

 Santiago (Chili), the work has entirely fallen through. 



Dr. Thome, of the Cordoba Observatory, has been enabled, 

 by the generosity of the Argentine Government, to volunteer for 

 the work assigned to La Plata ( - 24° to - 31°), and M. Enrique 

 Legrand stated that he had induced his Government to found an 

 observatory near Monte Video (Uruguay) to carry out the zone 

 ( - 17° to - 23°) allotted to Santiago. It was also suggested that 

 the new observatory at Perth, West Australia, might possibly 

 carry out the work on the remaining zone ( - 32° to - 40°). 



Another important item of the discussion was the advisability 

 of publishing the rectangular co-ordinates of the stars as 

 measured, with, of course, the constants of each plate, or delay- 

 ing the work until these could be transferred to equatorial co- 

 ordinates. It was considered that in the near future the 

 absolute positions of the comparison stars would be much more 

 accurately known than at present. The only drawback to this 

 scheme is that Dr. Scheiner, of Potsdam, has already started 

 the publication of the catalogue giving R.A. and Decl. of the 

 stars. 



In connection with the assignation of photographic magni- 

 tudes, it appeared to be generally believed that the estimation of 

 diameters by means of a scale is a surer plan than measurement 

 with a micrometer for this particular branch of work, but no 

 definite ruling was given on this point. 



The original plan agreed to in 1896 for taking the chart plates 

 with three exposures of 30m. each has not been followed at all 

 the observatories, and it was resolved at this meeting that in 

 future the method of taking the chart plates shall be decided by 

 the individual directors. In the reproduction of these chart 

 plates, it is unlikely that uniformity will be secured ; the French 

 observatories have made enlarged copies by heliogravure, but as 

 each observatory would have to expend some 10,000/. to do this, 

 the actual method of reproduction is left unsettled. 



Determination of Solar Parallax.— A circular has 

 been issued by the special committee appointed by the Inter- 

 national Astrophotographic Conference held recently at Paris 

 containing the resolutions passed for systematising the work to 

 be done at all the world's observatories during the coming 

 autumn and winter, when it is hoped, by means of observations 

 of the minor planet Eros, to determine the parallax and dis- 

 tance of the sun with a degree of accuracy previously unattain- 

 able. The following is a summary of the suggestions adopted : — 



(i) That the determination of parallax of Eros be made by 

 micrometric, heliometric and photometric measurements, (a) By 

 observations of the planet east and west of the meridian at the 

 same observatory, {b) By the co-operation of the observatories 

 of Europe and North America. (< }'By the co-operation of the 

 observatoiies of the northern and southern hemispheres. 



(2) During the period of parallax observations the diurnal 

 movement of Eros should be determined as accurately as poi- 

 sible by heliometer, micrometer and photography. 



(3) {a) Observers determining the parallax in right ascension 

 should make niea<;ures each night and morning, profiting by all 

 favourable circumstances to operate with as large hour angles as 

 possible, {b) Observers finding parallax by difference of de- 

 clination in northern and southern hemispheres, should arrange 

 that the mean instants of observation do not vary much from the 

 meridian passage of the planet at the southern station. 



(4) It is necessary that special series of photographs be taken 

 of the region traversed by Eros, in order to furnish accurate 

 determinations of the positions of comparison stars. 



As the varying atmospheric conditions will play an exceed- 

 ingly important part in the observations, particularly those 

 away from the meridian, MM. Andre and Prosper Henry have 

 been asked to prepare suggestions for eliminating these 

 difficulties. 



At the time of writing, the following observatories have 

 signified their intention of helping with the scheme: — Algiers, 

 Athens, Bamberg, B )rdeaux, Cambridge (England), Cambridge 

 (U.S.), Cape of Good Hope, Catania, Cordoba, Chicago 

 (Verkes), Edinburgh, Greenwich, Heidelburg, Leyden, Leipzig, 

 Lyons, Marseilles, Minneapolis (U.S.), Mount Hamilton 

 (Lick), Nice. Potsdam, Rome, San Fernando, Strassburg, 

 Tacuboya, Toulouse, Upsala, Vienna (Ottahring), Vienna 

 (Wahring), Washington. 



NO. 1607. VOL. 62] 



THE DISTANCE TO WHICH THE FIRING OF 

 HEAVY GUNS IS HEARD. 



TN a discussion which took place in Nature some time ago 

 on the so-called " Barisal Guns" and other mysterious 

 sounds. Prof. Hughes suggested that it would be desirable to 

 ascertain how far the firing of guns can be heard (vol. liii. p. 31). 

 In connection with another sul>ject, that of spurious earthquakes 

 (see Nature, vol. Ix. pp. 139-141), I have for some time been 

 collecting notes on this point, and I propose here to describe 

 some of the facts obtained, chiefly with regard to the great naval 

 review at Spithead on June 26, 1897, and the operations of the 

 French fleet at Cherbourg on July 18, 1900. 



I will mention first a few cases referring to more or less 

 isolated observations of the reports of distant guns. The firing 

 during the battle of Camperdown on October 11, 1797, is said 

 to have been heard in Hull, the distance between the two places 

 being more than 200 miles. A gentleman, formerly resident at 

 Kertch in the Crimea, informs me that he has heard the sound 

 of the guns fired at Sebastopol, distant 158 miles. During the 

 -Vmeiican Civil War, the roar of the guns at the battles of 

 Malvern Hill and Manassas (or Bull Run) was perceptible at 



