i6 



NATURE 



[November 7, 1895 



for any instant whatever. From the orbital velocity it is easy 

 to deduce the length of the semi-axis major of the orbit, and the 

 parallax is equal to the semi-axis major in seconds of arc, divided 

 by the length of the same when expressed in astronomical units. 

 The sum of the masses follows from the ordinary application of 

 Kepler's third law. Dr. See lays special stress upon the im- 

 portance of these investigations being taken up practically, as 

 they will furnish us with "an absolute parallax exact to the 

 highest degree," and will also enable us to apply a rigorous test 

 of the universality of the law of gravitation. It is known 

 already, from micrometrical measures, that Kepler's second law 

 holds good for binary stars, and therefore that the force is cen- 

 tral ; but it remains to be shown that the principal star is in the 

 focus of the real ellipse. 



The Solar Parallax. — Among the various methods 

 suggested as suitable for the determination of the solar 

 parallax, that afforded by the parallactic inequality in the motion 

 of the moon deservedly takes a high place. The reason is that 

 in this particular term the parallax of the sun is multipUed 

 by a coefficient which increases the quantity to be deter- 

 mined in the approximate ratio of i : 15, so that an error 

 of a tenth of a second in the inequality would not pro- 

 duce an error of one-hundredth in the parallax sought. But 

 in deriving the solar parallax it is necessarily assumed, that the 

 relation between these quantities is accurately given by theory. 

 Unfortunately there has been a discrepancy between the co- 

 efficients derived by Hansen and Delaunay, and the accepted 

 explanation has not been the correct one. In order to ensure 

 identity between Hansen and Delaunay it was necessary to 

 suppose than an error existed in the highest term computed by 

 Delaunay, and that the deviation of the remaining terms from 

 the general character of the series did not exist. Recent work 

 by Mr. Hill and Prof Brown has, however, confirmed the 

 accuracy of Delaunay's theory so far as this particular term is 

 concerned, though it leaves a general doubt on the legitimacy of 

 neglecting the higher terms in some of the series in other parts 

 of the theory. Prof. Newcomb points out {Astronom. Jour. No. 

 356) that this more recent discussion of Messrs. Hill and Brown 

 demands an increase on the theoretical value of Hansen, on 

 which he had previously relied, of o""30, and consequently a 

 diminution in the solar parallax of o" "021 giving the corrected 

 value of ir = 8"773. 



THE EPPING FOREST MUSEUM AT 

 CHINGFORD. 

 'T^HE opening of this museum, which we announced in our 

 last week's issue as having been fixed for Saturday, 

 November 2, was in every respect an interesting ceremony, and 

 marks a period in the history of the Essex Field Club, of which 

 this active society may well feel proud. Two or three years after 

 the foundation of the Club in 1880, an informal meeting was held 

 at the residence of Mr. E. N. Buxton, with a view to starting such 

 a local collection, but the Conservators at that time had not long 

 been in charge of the Forest, and they did not see their way to 

 giving house-room for the museum in the old lodge known as 

 " Queen Elizabeth's." The founders of the Club, however, have 

 never lost sight of the desirability of having such a collection in 

 the Forest district, and in February 1894, a special meeting of 

 local residents and others was convened, and a local sub-com- 

 mittee formed for the purpose of forwarding the scheme. A 

 subscription list was opened, and a sufficient sum raised to war- 

 rant another application to the Conservators for the use of Queen 

 Elizabeth's Lodge. This was granted, and the Banqueting 

 Room, which from time immemorial has been unoccupied and 

 devoid of fittings, has now undergone transformation into a 

 museum, which was declared open to the public as a part of 

 Saturday's proceedings. The arrangement of the collections, 

 illustrating the natural history, geology, archaeology, and topo- 

 graphy of the Forest, has been entirely carried out by Mr. 

 William Cole, the Hon. Secretary of the Club, aided by his 

 brothers and a few zealous workers who gave their co-operation, 

 notably Messrs. W. Crouch, I. Chalkley Gould, A. Greenhill, 

 and others. On Saturday afternoon a very representative 

 gathering of scientific men took place at Chingford, to assist at 

 the opening ceremony. The members and guests, comprising 

 among the former Sir William Flower, Mr. Edward North 

 Buxton, Profs. R. Meldola and G. S. Boulger, Mr. J. E. 

 Harting, &c. , and among the latter a large number of the Epping 



NO. 1358, VOL. 53] 



Forest Committee of the Corporation of London, were received 

 by the President of the Club, Mr. David Howard, in a room ad- 

 joining the museum. After a few introductory remarks by the 

 President, Sir William Flower addressed the meeting on the 

 general subject of local museums and the advantages to be de- 

 rived from their establishment. Mr. Deputy Halse, the Chair- 

 man of the Epping Forest Committee, then expressed, on. 

 behalf of the Corporation, the satisfaction which they all felt in 

 being associated with the Essex Field Club in the movement, 

 and declared that from Monday, the 4th, the collections would 

 be available for public inspection. The party then proceeded to 

 view the museum, and great satisfaction was expressed at the 

 large amount of material which had been brought together in a 

 comparatively short time and with very modest financial 

 means. Mr. Greenhill's collection of flint implements from 

 the valley of the Lea, Mr. T. Hay Wilson's set of drift 

 rock materials from the local glacial gravels, Mr. Crouch's 

 shells of the Dengey Hundred, the cabinets of Forest 

 flowering plants, fungi and insects, and the interesting set 

 of relics found during the Club's explorations of the Forest 

 earthworks, were all much admired. A pamphlet by Mr. 

 Chalkley Gould, being one of a proposed series of museum 

 handbooks, was distributed at the meeting. The author 

 in this pamphlet gives a description of the Romano- British 

 station at Chigwell in illustration of the specimens which he has 

 contributed to the museum. After the inspection the party 

 assembled for tea at the Royal Forest Hotel, some eighty or 

 ninety members and visitors being present. At a meeting of 

 the Club, held after tea, the President moved a vote of 

 thanks to Mr. William Cole and his coadjutors foir the large 

 amount of work which they had voluntarily done on behalf of 

 the museum. This was warmly seconded by the Rev. A. F. 

 Russell, the rector of Chingford, who is chairman of the local 

 sub-committee. Mr. Cole having acknowledged the vote of 

 thanks, Mr. A. Smith Woodward (of the British Museum) then 

 gave a short address, in the course of which he pointed out the 

 essential requirements that the museum should fulfil in order to 

 be of real use, and commented most favourably upon the arrange- 

 ment of the collections, their contents, and their mode of display. 

 Sir William Flower expressed his concurrence with Mr. Wood- 

 ward's remarks, and made some further observations and sug- 

 gestions, especially dwelling upon the importance of taking steps 

 to insure the permanence of the museum when those who had 

 laboured so well for its foundation were no longer able to carry 

 on the work. In the course of his remarks he paid a high 

 tribute to the general work of the Essex Field Club, of which 

 he had been an honorary member almost from the time of its 

 foundation. Prof Meldola, in proposing a vote of thanks to 

 Mr. Deputy Halse, pointed out that the element of permanence 

 to which Sir William Flower had alluded was most likely to 

 accrue from their association with the Epping Forest Committee. 

 This vote having been seconded by Mr. E. N. Buxton, and re- 

 plied to by Mr. Halse, Mr. Harting made some remarks on the 

 danger of encouraging promiscuous " collecting" by schoolboys, 

 and the proceedings terminated. Favoured by an exceptionally 

 brilliant autumnal afternoon, the meeting was a distinct success, 

 and must have given great satisfaction to its promoters. The 

 museum is necessarily small, but a good beginning has been 

 made, and the time may be looked forward to when increased 

 accommodation will be required. The feature which most 

 strongly commends it to students of natural science, and lovers of 

 the Forest generally, is the purely local character of the col- 

 lections. No more appropriate use of Queen Elizabeth's Lodge 

 could possibly have been made, and the Corporation of London 

 have done wisely in allowing the Essex Field Club to found an 

 institution which, however small and unpretentious, is, even as 

 at present appointed, a distinct boon to all frequenters of the 

 Epping Forest district. 



CONCENTRATION OF GOLD ORES> 

 'VAT'HEN gold mining is a new industry in any country, the 

 methods of extraction are often somewhat rough and 

 ready. With great quantities of rich ore waiting for treatment 

 or easily obtainable, the mill-man is usually intent on obtaining 

 the greatest possible quantity of bullion in a short time, rather 

 than on establishing a good system of reduction, which in the 

 1 " Report on the Loss of Gold in the Reduction of Auriferous Veinstone in 

 Victoria." By Henry Resales. (Issued by the Department of Mines, 

 Melbourne, 1895.) 



