April 19, 1888] 



NATURE 



585 



water. Then, Mr. Reade supposes all the organisms in the 

 bulk of water taken to die and fall to the bottom each day. 

 Mr. Murray, in his calculations, supposes only one-sixteenth 

 part to die each day. From the same data the former makes 

 out a rate of accumulation of deposit of I inch in 29 years, 

 the latter a rate of i inch in 470 years. Dana estimates 

 the growth of a reef at not greater than oiie-sixteenth of an inch 

 in one year, i.e. i inch in 16 years. Yet it will be admitted 

 that a reef must grow much more rapidly than a deep-sea 

 deposit. What then would justify us in accepting these figures 

 as in any way representing what is now taking place in Nature? 

 The fact is we much want definite information on the rate of 

 growth of these calcareous deposits, and if Mr. Reade has the 

 information his language would warrant, he should make it 

 known for the benefit of science. 



We know that these deposits do accumulate to hundreds of 

 feet in thickness in some places, notwithstanding solution ; and 

 it seems to me that, as we can imitate in the laboratory the 

 conditions of solution while we cannot those of secretion by 

 organisms, then by experiments in this direction we may at 

 least arrive at a knowledge of the minimum rate of accumulation 

 of oceanic calcureous deposits. James G. Ross. 



14 Argyll Place, Edinburgh, April 14. 



Beinicle Geese on Coniston Lake. 



This afternoon while walking by this lake I saw four large 

 birds flying overhead. These birds, after making several circuits 

 in the air, pitched on the lake. I had with me an excellent pair 

 of field-glasses, and as I succeeded in approaching within 20 

 yards of them, I was enabled to examine them with sufficient 

 accuracy to convince me that they were Bernicle geese {Anser 

 leucopsis, Yarrell). What struck me as most worthy of remark 

 was their extreme tameness, as they allowed me, first on land, 

 and then in a boat, to approach within 20 yards of them. They 

 were in excellent plumage, and seemed in good condition. After 

 remaining about three hours swimming about on the lake, they 

 rose, and after circling round once or twice, flew off in a northerly 

 direction. 



May I ask if this is a rare bird to see in the Lake District 

 at this time of year? I have inquired in the neighbourhood, 

 and do not think they could have come from any private water. 

 Several people who have been here for many years assure me 

 they have never seen this bird on the lake before, and this has 

 certainly been my own experience. Is it possible their extreme 

 tameness was due to fatigue? William R. Melly. 



Tent Lodge, Coniston Lake, Lancashire, April 8. 



The Muzzling of Oysters. 



This practice, described in the current number of Nature 

 (p. 572) as owing "its existence to a careful study of the habits 

 of the bivalve," is by no means new, though probably original on 

 the part of the American naturalists. Our London fishmongers 

 have muzzled oysters on a large scale from a time that is im- 

 memorial among them. Barrelled oysters are all very care- 

 fully muzzled, but without wires, as anybody may learn by 

 watching an expert in the process of barrelling. It will be seen 

 that he lays the oysters one by one carefully in tiers up to the 

 top of the barrel, and then lays another tier xxswi^above the level 

 of the lop. Having done this, he places the lid of the barrel on 

 this exuberant tier, and thumps and rattles the barrel on a stone 

 pavement or other solid ground until, by close packing of the 

 whole, it descends to the level of the barrel top. The mass of 

 oysters being thus compressed so as to render the slightest gaping 

 of any one quite impossible, he firmly nails down the head of the 

 barrel. 



Experience has proved that oysters thus effectively muzzled 

 may take long slow journeys (as they did in the old coaching 

 days) and be kept fresh and without loss of flavour for two or 

 three weeks, provided the barrels are unopened. If, however, 

 they are loosely barrelled, a few days are too many. In some 

 old country houses the barrels, unopened, were placed in salt 

 water, and thus kept until required, but whether this was 

 advantageous I cannot say. 



W. Mattieu Williams. 



The Grange, Neasden, April 13. 



SUGGESTIONS ON THE CLASSIFICATION OF 

 THE VARIOUS SPECIES OF HEAVENLY 

 BODIES} 



I. 



I.— PROBABLE ORIGIN OF SOME OF THE GROUPS. 



I. Nebulae. 



IN a paper communicated to the Royal Society on 

 November 15, 1887, I showed that the nebulae are 

 composed of sparse meteorites, the collisions of which bring 

 about a rise of temperature sufficient to render luminous 

 one of their chief constituents — magnesium. This con- 

 clusion was arrived at from the facts that the chief nebula 

 lines are coincident in position with the fluting and lines 

 visible in the bunsen burner when magnesium is intro- 

 duced, and that the fluting is far brighter at that tempera- 

 ture than almost any other spectral line or fluting of any 

 element whatever. 



I suggested that the association or non- association of 

 hydrogen lines with the lines due to the olivine constituents 

 of the meteorites might be an indication of the greater or 

 less sparseness of the swarm, the greatest sparseness 

 being the condition defining fewest collisions, and there- 

 fore one least likely to show hydrogen. This suggestion 

 was made because observations of comets and laboratory 

 work have abundantly shown that great liability to colli- 

 sion in the one case, and increase of temperature in the 

 other, are accompanied by the appearance of the carbon 

 spectrum instead of the hydrogen spectrum. 



The now demonstrated meteoric origin of these celestial 

 bodies renders it needful to discuss the question in some- 

 what greater detail, with a view to classification ; and to 

 do this thoroughly it is requisite that we should study the 

 rich store of facts which chiefly Sir William Herschel's 

 labours have placed before us regarding the various forms 

 of nebulae, with the view of ascertaining what light, if 

 any, the new view throws on their development. 



To do this the treatment must be vastly different from 

 that — the only one we can pursue — utilized in the case of 

 the stars, the images of all, or nearly all, of which appear 

 to us as points of light more or less minute, while, in the 

 case of the nebulas, forms of the most definite and, in 

 many cases, of the most fantastic kind, have been long 

 recognized as among their chief characteristics. 



It will at once he evident that since the luminosity of 

 the meteorites depends upon collisions, the light from 

 them, and from the glow of the gases produced from them, 

 can only come from those parts of a meteor-swarm in 

 which collisions are going on. Visibility is not the only 

 criterion of the existence of matter in space ; dark bodies 

 may exist in all parts of space, but visibility in any part 

 of the heavens means, not only matter, but collisions, or 

 the radiation of a mass of vapour produced at some time 

 or other by collisions. The appearances which these 

 bodies present to us may bear little relation to their 

 actual form, but may represent merely surfaces, or loci of 

 disturbances. 



It seemed proper, then, that I should seek to determine 

 whether the view 1 have put forward explains the pheno- 

 mena as satisfactorily as they have been explained on the 

 old ones, and whether, indeed, it can go further and make 

 some points clear which before were dark. 



To do this it is not necessary in the present paper to 

 dwell at any great length either on those appearances . 

 which were termed nebitlosities by Sir William Herschel 

 or on irregular nebulas generally ; but it must be remarked 

 that the very great extension of the former — which there 

 is little .reason to doubt will be vastly increased by 

 increase of optical power and improvement in observing 

 conditions and stations — may be held to strengthen the 

 view that space is really a meteoritic plenum, while the 

 forms indicate motions and crossings and interpenetra- 



■ The Bakerian Lecture, delivered at the Rojal Society on April 12, by 

 J. Norman Lockyer, F.R.S. 



