8 



NATURE 



[May 2, 1872 



the movement ; a temporary committee was formed, and 

 lists of subscribers and donors were at once commenced. 

 By a curious coincidence, the telegram announcing' 

 the formation of the Society no sooner came under 

 the notice of the Colonial Government, than they 

 informed the committee that they had, a short time 

 before, received a communication from the Imperial 

 authorities on the subject. The Astronomer Royal had 

 intimated his desire to form a station in New Zealand for 

 the observation of the Transit of Venus in 1874, and had 

 recommended Canterbury as suitable for the purpose. 

 This announcement was naturally most encouraging to 

 the committee ; steps were immediately taken by them to 

 communicate, through His Excellency the Governor, 

 with the Imperial Government. The Governor and 

 his advisers have informed the Society that they cordially 

 approve of its object, and will assist it as far as possible. 



The Provincial Council of Canterbury was in session a 

 few days later. Petitions were presented to it by the 

 Society, praying for a grant of 1,000/. towards buildings, 

 &c.. and 5,000 acres of the waste lands of the province as 

 an endowment towards the permanent maintenance of 

 the Observatory. The Council, by a majority of twenty- 

 five to eleven, voted the sum of 1,000/., and 200/. for a 

 site ; but they declined at present to grant the endow- 

 ment in land. The money grant of 1,200/. was likewise 

 made conditional on the agreement of the Colonial 

 Government to undertake the maintenance of the Insti- 

 tution. The great interest taken in the movement by His 

 Excellency the Governor and his Ministers leads the 

 Society to hope that a satisfactory arrangement may be 

 made, so that before this time next year we may be placed 

 in a position actually to commence operations. 



Although only a month has elapsed since the first meet- 

 ing, the Society has been warmly supported in this pro- 

 vince. Additional subscriptions are received every day, 

 and since January 22, when the temporary committee 

 presented their report, the number of annual members 

 has been increased to nearly 200. 



I enclose the report of the temporary committee, which 

 details the work actually done by them so far. You will 

 see that the committee have attempted to commence the 

 practical work of founding the Society by asking the 

 Astronomer Royal to send out a gentleman to advise as 

 to a proper site and other initiatory work. It is our hope 

 that our object may receive a cordial concurrence from 

 scientific men at home. We desire to co-operate with 

 similar institutions in the old world by performing work 

 which may not only be of practical use to our community 

 here, but may, if possible, add something, however small, 

 to the results of labours of older workers in the field of 

 science. We trust that even one of England's youngest 

 daughters may be of some assistance in this respect to 

 her more favoured sisters. 



W. M. Maskell, Hon. Sec. 

 Observatory Society of Canterbury. 



A NEW MODE OF TAKING CASTS 



MR. BOYD DAWKINS, F.R.S., has recently exhibited 

 to the Manchester Philosophical Society a number 

 of casts in plaster of Paris of various objects of natural 

 history, and explained the process by which any one can 

 make them for himself The material of the mould is 

 artists' modelling wax, which is a composition akin to that 

 which is used by dentists. And as it becomes soft and 

 plastic by the application of heat, though in a cold state 

 it is perfectly rigid, it may be applied to the most delicate 

 object without injury. As it takes the most minute mark- 

 ings and striations of the original to which it is applied, 

 the microscopic structure of the surface of the original is 

 faithfully reproduced in the cast. The method is briefly 

 this : — I. Cover the object to be cast with a thin powder 



of steatite or French chalk, which prevents the adhesion 

 of the wax. 2. After the wax has become soft either from 

 immersion in warm water or from exposure to the direct 

 heat of the fire, apply it to the original, being careful to 

 press it into the little cavities. Then carefully cut off the 

 edges of the wax all round, if the under cutting of the 

 object necessitates the mould being in two or more pieces, 

 and let the wax cool with the object in it, until it be 

 sufficiently hard to bear the repetition of the operation on 

 the uncovered portion of the object. The steatite pre- 

 vents the one piece of the mould sticking to the other. 

 The original ought to be taken out of the mould before 

 the latter becomes perfectly cold and rigid, as in that case 

 it is very difficult to extract. 3. Then pour in plaster of 

 Paris, after having wetted the moulds to prevent bubbles 

 of air lurking in the small interstices, and if the mould be 

 in two pieces, it is generally convenient to fill them with 

 plaster separately belore putting them together. 4. Then 

 dry the plaster casts either wholly or partially. 5. Paint 

 the casts in water colours, which must ht fainter than 

 those of the original, because the next process adds to 

 their intensity. The delicate shades of colour in the 

 original will be marked in the cast by the different quantity 

 of the same colour which is taken up by the different tex- 

 tures of the cast. 6. After drying the cast, steep it in 

 hard paraffin. The ordinary paraffin candles, which can 

 be obtained from any grocer, will serve the purpose. 

 7. Cool, and polish the cast by hand with steatite. The 

 result of this process is far better than that obtained by 

 any other. The whole operation is very simple, and 

 promises to afford a means of comparison of natural 

 history specimens in different countries, which has long 

 been felt to be a scientific need. It has been already 

 introduced into America and India by Mr. Dawkins, and 

 samples of the casts are to be seen in the British Museum, 

 as well as in that of the Geological Survey, and of Oxford, 

 and of the Queen's College. Casts of type specimens may 

 be multiplied to any extent at a small cost of time and 

 money, and are as good as the original for purposes of 

 comparison, and almost as hard as any fossil. 



The modelling wax can be purchased from Messrs. 

 Lechettier, Barbe, & Co., artists'-colourmen. Regent Street. 



THE NEBULA ROUND V ARGUS 



A PAPER, accompanied by five drawings, has recently 

 been read to the Royal Society of Victoria by Mr. 

 McGeorge, on the star i; Argus and the great nebula 

 near it, from which we select a few statements which 

 appear to establish the occurrence of sensible changes 

 in that region of the sky. After noticing the value 

 of Sir John Herschel's drawing and description of the 

 nebula, Mr. McGeorge remarks that from 1838 to 

 1869 no trustworthy observations of the nebula could 

 be made, for want of instruments of sufficient power; 

 though Mr. Tebbutt and others have contributed valuable 

 information about r; itself. A single glance is sufficient 

 to show the complete inapplicabiluy of Herschel's draw- 

 ing or description to the present appearance of the 

 nebula in the Great Melbourne Telescope. This, how- 

 ever, might be attributed to the great power of the in- 

 strument, whose light exceeds that of the 20-ft. reflector 

 as much as that surpassed the other telescopes with 

 which the nebula has been observed. 



But the changes indicated in the present paper cannot 

 be so explained, for they have nearly all been traced in 

 the GreiU Melbourne Telescope itself, and are described 

 in detail, with reference to drawings and observing notes. 

 A few may be mentioned here. 



r\, which Herschel saw involved in dense nebula, was 

 in April 1869 seen on the bare sky, the nebula having 

 disappeared for some distance around it. Drawing No. i, 

 which accompanied thepaper and which is here reproduced, 



