lo 



NATURE 



[May 4, 1876 



a dwarf in comparison with those seen by Mr. Munro and Mr. 

 Quin. Doubtless the broken-down and pulverised corallines 

 fill up many a crack in the reefs limestone. Should Mr. Munro 

 be desirous of seeing some of his old West Indian corallines, I 

 shall be glad to show him some microscopical results of work 

 upon them. P. Martin Duncan 



Geological Society, May i 



History of Magnetism 



A PARAGRAPH in the article on ' ' The Early History of Mag- 

 netism," in your last number, contains a passage which requires, 

 I think, a note of explanation. The writer says : "A Latin 

 letter ascribed to Peter Adsiger, 1269, preserved among the 

 manuscripts of the University of Leyden, contains the following 

 remark on the declination of the needle ..." Now Hum- 

 boldt, on the authority of Libri, denies the existence of the 

 passage in the Leyden MSS., affirming that it is only an inter- 

 polation in a Paris copy. But what is of more importance, he 

 also states that the title of the letter is "Epistola Petri P. de 

 Maricourt ad Sigernum de Foucoucourt, " E. Walker, in his 

 well-known essay on Magnetism, refers to Cavallo as quoting 

 the supposed letter of Adsiger. S. J. Perry 



Meteorological Society 



While thanking you for your friendly notice of the Annual 

 Report of this Society, I trust you will allow me to state that 

 we have not made ' ' the mistake in science regarding the height 

 of the thermometers above the ground," as very naturally ima- 

 gined by you from the matter not having been mentioned. The 

 fact is, we have been unusually strict on that point ; our ther- 

 mometers are all 4 feet (within, perhaps, 2 in. -J- or — ), and as 

 the uniformity was so strict, it was considered useless to repeat 

 the statement for each station, and so, finally, it escaped mention 

 altogether in the printed abstract. Of course the question 

 (Report, p. 52), *' What is the height of the bulbs above grass ? " 

 is duly answered on the MS. inspection forms deposited in the 

 library of the Society. 



May I, in conclusion, express the hope that the example which 

 we have set by publishing the lithograph ground-plans, and 

 which you so highly approve, may be generally followed both 

 in this country and abroad? G. J. Symons 



Meteorological Society, 30, Great George Street, 

 Westminster, S.W., April 28 



Destruction of Flowers by Birds 



The enclosed blossoms of the common "wild" cherry 

 {Prunus avium, L.) have been mutilated in a precisely similar 

 manner with those of the blackthorn noticed about a year ago in 

 Nature (vol. xii. p. 26), the petals and stamens still adhering 

 to the separated limb of the calyx, which has been cut through 

 at the exact level of the ovary, which has perhaps been the 

 object of attack. Orchard trees in the neighbourhood from the 

 same stock have also suffered to a serious extent, but the wall- 

 cherries (P. cerasus, L.), which are later in flowering, have 

 hitherto been untouched. R. A. Pryor 



Hatfield, May 2 



OUR ASTRONOMICAL COLUMN 

 The Nebula in Orion.— M. Tisserand, Director of 

 the Observatory at Toulouse, commenced on Feb. 17 

 of the present year, a close examination of the small stars 

 in the vicinity of the trapezium in the great nebula of 

 Orion, with the Foucault telescope of o'"-8o aperture, 

 which had been completely mounted at the beginning 

 of the same month. To facilitate the study of this 

 region, which it is intended shall form part of the work 

 with this fine instrument, a chart was prepared on a large 

 scale containing the 155 stars, the positions of which 

 relatively to 6^ Orionis, were determined by M. O. Struve 

 {Observations de la Grande Nebuleuse d' Orion in the St. 

 Petersburg Memoirs, vol. v.); of these 155 stars it may 

 be mentioned that 150 occur in Sir John Herschel's list 

 in the volume of observations made at the Cape of Good 

 Hope. Especial attention was directed at Toulouse during 

 the few weeks that the nebula could be observed in the last 



season, to the stars which M. O. Struve had indicated as 

 variable. The star IT (Aa . . — 7"-3, AS . . - 27"-6) 

 which is not in Herschel's catalogue, was noted on Feb. 

 17 and 21 at the extreme limit of visibility : on following 

 days, when the sky was more transparent, it could not be 

 discerned ; at maximum according to Struve this star 

 is of the twelfth magnitude, the smallest star which can 

 be distinctly seen in the Pulkowa refractor being con<- 

 sidered 13*5 — a very different scale of magnitude, it will 

 be remarked, from that of Bessel ; No. 78 (Aa . . . --t-34"'5> 

 AS ... + 9"7), varying, according to Struve, from 12*5 

 to invisibility, was not discerned ; No. 75 (Aa . . . + 21 '''•3, 

 AS . . . 4- 39"'2) was 14-15 on March 14; Tisserand 

 found No. V. of the Pulkowa list (Aa . . . + 378"'3, 

 AS ... + 66"'3) extremely faint on Feb. 24, and quite 

 invisible subsequently, whence he concludes this star to 

 be also variable, and that its non-insertion by Herschel 

 may have arisen from its bemg at a minimum at the 

 epoch of his observations. 



Thirty-two stars have been remarked at Toulouse, 

 which are not in the Pulkowa catalogue ; of these fifteen 

 occur in Bond's catalogue, in vol. v. of " Annals of the 

 Harvard Observatory " ; the remaining seventeen which 

 have not, as it appears, been previously observed, are 

 generally very faint, the only notable exceptions being in 

 the cases of two stars, which have the following estimated 

 co-ordinates relative to 6^. 



Ao ■\- 180" ... A5 - 180" 



» - 110" ... ,, - 480" 



The first star was 13 (an object termed tres belle with the 

 Toulouse instrument) on February 17, but had become 

 extremely faint on March 14 and 26. The second star is 

 estimated 13, almost as bright as its neighbour, No. 55 of 

 Struve's catalogue. M. Tisserand states that he has not 

 been able to recognise all the stars in Bond's catalogue, 

 more paiticularly in the neighbourhood of the trapezium. 



The numerous variable stars, which we have now reason 

 to suppose exist in the nebula of Orion, certainly form 

 one of the most significant and interesting features in the 

 history of that grand object. 



It may be added here that M. Tisserand has also em- 

 ployed the powerful optical means now at his command, 

 upon observations of the satellites of Uranus. 



New Minor Planets. — Still another small planet is 

 announced during the last week. It was found by M. 

 Perrotin at Toulouse on April 26, in R.A. I4h. iim. 48s , 

 N. P. D, 96° 24' ; twelfth magnitude. 



The planet detected by Prof. Watson at Ann Arbor on 

 April 19 is called No. 161 in the Astronomische Nach- 

 richten. These numbers, however, are now in much 

 confusion, and names for those which are observed a 

 sufficient length of time to allow of the determination of 

 elements have an obvious advantage over the system of 

 leaving these planets to be distinguished by a number 

 only. As regards numbers there is even doubt as far 

 back as No. 149, which has not yet been shown to be 

 distinct from Frigga (No. 'j'j). 



Biela's Comet and the November Meteor-Stream. 

 — If we take for the orbit of the November meteor-stream 

 the elements calculated by Prof. J. C. Adams, and com- 

 municated to the Royal Astronomical Society in April, 

 1867, and for Biela's comet a mean of the sets of elements 

 for the two nuclei in 1866, given by Clausen in " Melanges 

 Mathematiques et Astronomiques," &c., t. iii., of the Im- 

 perial Academy of St. Petersburg, we find for the least 

 distance between the tracks of the comet and the meteors, 

 0*054, the mean distance of the earth from the sun being 

 taken as unity. This nearest point of approach is in 

 heliocentric longitude 61° 30' (equinox of 1866), where we 

 have — 



Comet. Meteors. 



Heliocentric latitude ... 0° 58' N. 2° 57' N. 



True anomaly 311° 44' 356° 24' 



Radius-vector 1*0266 0*9865 



