May 4, 1876] 



NATURE 



Harris, of what is regarded by every Palaeontologist who has seen 

 the specimen as an unquestionable organism. It forms part of 

 a limestone bed intercalated with dark grey shale, and occurs in 

 the midst of highly metamorphic rocks (among them a graphite 

 granite), which were regarded by Sir Roderick Murchison as of 

 Laurentian age, and which have ever since passed as such — no 

 doubt being entertained as to their antiquity by Dr. Heddle, 

 of St. Andrew's, who has geologised over the whole of Harris. 



Judging from the sections which Mr. Thomson has forwarded 

 to me, the fabric seems to have consisted of superposed layers of 

 calcareous shell-substance, whose continuity is frequently inter- 

 rupted ; the spaces between these layers, which are much thinner 

 than the lamellae themselves, being irregularly and imperfectly 

 divided (very much as in Eozoon) into separate chambers, which 

 are filled up with calcite. The state of preservation of the fossil 

 thus corresponds exactly with that of the Silurian Strcmaiopora, 

 to which, indeed, it bears a strong general resemblance, except 

 in the larger proportion borne by the solid fabric to the chambers 

 it encloses. The shelly layers are as distinct in character from 

 the calcite contents of the chambers, as are those of the Nummu- 

 lites of the pyramid-limestone, with which they agree in their 

 remarkable hardness, corresponding with that of porcellanous 

 shell. Altogether I have no hesitation in concurring with Prof. 

 H. A. Nicholson, Prof. Geikie, and Mr. Etheridge in affirming 

 it to be so unmistakeably organic, that, if it be claimed by 

 mineralogists as a "rock-structure," a large number of uni- 

 versally-accepted fossils will have to go along with it. As it is 

 essentially calcareous in its composition, there is no room for the 

 hypothesis of its production by the process of *' mineral segrega- 

 tion," which is maintained by certain Mineralogists (others of at 

 least equal eminence, however, entirely dissenting from them) to 

 have been adequate to the production of the alternating layers of 

 serpentine and calcareous shell-substance in the Canadian Eozoon, 

 And though mineralogical analysis might not improbably detect 

 small particles of various minerals in its substance, their presence 

 no more establishes its claim to be regarded as a mere rock- 

 structure, than does the presence of siliceous films (probably re- 

 placing the soft parts of the animal) in a piece of coral-limestone. 



Not having made any other than a general examination of the 

 structure of the Harris specimen, I do not feel able to give a 

 positive opinion upon its affinities ; and it may be that these 

 may long remain doubtful. But ;his doubt no more constitutes 

 an adequate reason for refusing to accept its organic origin, than 

 it does in the case of Stromatopora ; which no Mineralogist that 

 I ever heard of claims as a mineral, though the Zoologist cannot 

 say with certainty whether it is a foraminifer, a sponge, a coral, 

 or a polyzoary. It is to be borne in mind that in very few 

 Palaeozoic fossils is there a precise conformity to any existing 

 type ; and such conformity is, of course, still less to be expected 

 in a Laurentian than in a Silurian fossil. 



It is not a little singular that I should have received about the 

 same time from Prof. Mobius of Kiel, specimens of a new Fora- 

 miniferal organism, discovered by him in 1874 on a coral reef off 

 Mauritius ; which presents more resemblance in its spreading and 

 encrusting mode of growth to the indefinite expansions of Eozoon 

 and Stromatopora, than does any Foraminiferal type previously 

 known. Truly, as I have before had occasion to say, "there is 

 no limit to the possibilities of Foraminifera. " 



I have only to add, in regard to the Harris fossil, that the 

 further prosecution of the inquiry into its structure and relations 

 has been placed by Mr. Thomson in the able hands of Prof. H. 

 Alleyne Nicholson, and that it is at the joint request of these 

 two gentlemen that I make the present communication. 



William B. Carpenter 



The Warm Rain Band in the Daylight Spectrum 



On taking my accustomed spectroscopic peep at the sky to- 

 day, through a little garret window in the Royal Observatory 

 here, I was instantly struck with the presence of the same dark 

 band in the spectrum to which I called your attention last 

 summer twice over (vol. xii. pp. 231, 25")' 



The band was very faint, but it was there, and this was its 

 first appearance, to me at least, during the present year. I have 

 not indeed been so persevering in that sort of observation as I 

 perhaps should have been if furnished with better instruments, 

 yet for weeks and weeks past I have scanned the sky, not only 

 when it was heavily clouded, but also when rain was actually 

 falling with west, south-west, and north-east winds, and some- 

 times during dense, wet fogs,; when very little daylight at 

 all was left, and under some preternaturally low barometric 



pressures. Yet, under all these circumstances, I put the 

 spectroscope back into its box after each trial with the 

 assurance that no rain-band had then been shown by it. 

 This morning, however, and under a barometer not low, 

 viz., 29*8 British inches, the band exhibited itself instantly ; 

 and on my going out to look at the directi' n of the wind, 

 behold it was from the south-east. Wherefore I had nb 

 scruple in informing a professor whom I met in the afternoon at 

 the College, and who, after his day's work there was going 

 home to indulge in the amenities of horticulture, that his flowers 

 were certain of presently having the luxury of warm rain. 



Such rain, too, did begin, within an hour of that interview, 

 with large heavy drops, and the evening has ended with almost 

 a soaking rain. 



It is rather too soon to attempt fully to describe the spectrum 

 appearance, much less to explain it, before I have had the privi- 

 lege of using anything in the way of a notable spectroscope upon 

 it. But having been already written to for some practical infor- 

 mation, even from St. Petersburg (where Nature is evidently 

 read with attention), I may remark that the nebulous band cha- 

 racter of the phenomenon is simply a result of want of light ; 

 for when the quality to give the band was present in the air, and 

 the sun has been prevailed on to shine for a moment through 

 that air, and into the spectroscope, the band was instantly re- 

 solved into a group, or groups, of fine and sharp black Imes, 

 exquisitely visible. 



But as the sun is seldom to be seen in any weather threatening 

 rain, whether warm or cold, in fact, cannot be consulted precisely 

 at those times when he is most wanted, it is better to restrict 

 such pluvio-spectroscopy to ordinary sky, i.e., clouds or air ; and 

 if possible in a polar direction, so as to be equally di slant from 

 the sun, whether visible or not, all the day through ; and 

 not too low, in altitude, lest smoke, local moisture, and other 

 impurities have too great and variable an influence. The Ob- 

 servatory garret-window here, I regret to say, is not so unexcep- 

 tionably situated in azimuth as it might be, for it looks out 

 straight to the south, and the angle at which I usually look 

 through it, on being measured to-day, turned out to be 23*. 



Nevertheless, at that altitude, keeping to it steadily on al^ 

 occasions, and in that direction, avoiding always the garish 

 spectra of actual sunshine, and depending not on any particular 

 and absolute spectrum representation in the published maps of 

 other observers, but chiefly or entirely attending to the differences 

 observed by myself from day to day in my own manner with my 

 own little tube, there was no difficulty in instantly pronouncing 

 this morning that there was something in the air through which 

 daylight was then passing different from what it has been for 

 several months past. 



Whether that something is only watery vapour at a high tem- 

 perature (seeing that watery vapour at a low temperature does 

 not produce it), or whether the air is carrying something else 

 with it, giving to the south-east winds here a slight approach to 

 the quality of the siroccos of the Mediterranean, which are often 

 transfused with fine dust along with their warm rain, and do 

 produce some very noteworthy markings in the spectrum, is a 

 matter for further and wider research by those who are instru- 

 mentally and financially better able to follow it up ; and who 

 should therefore be implored in the present state and needs of 

 science to perform their part without further delay. 



Pjazzi Smyth, 



Edinburgh, April 24 Astronomer- Royal for Scotland 



Limestone Makers 



Mr. J. MUNRO'S interesting letter and sketch which appeared 

 in Nature, vol. xiiL p. 510, show how much may be done in 

 the Tropics by ordinary observers towards elucidating many 

 geological problems. His sketch is that of one of the genus 

 Corallina, a member of the Florideae, and it is a very common 

 lime maker at the Bermudas. Although Mr. Munro will not 

 find a list of the different limestone makers in books, still in the 

 vast imwritten knowledge of geology it is well known that shells, 

 foraminifera, serpulae in numbers, and huge masses of NuIH- 

 pores, besides the corallines, contribute to the coral stock. 



The corallines present many and varied forms on our own 

 coasts, but their beauty and construction are remarkable in the 

 warm waters of the Gulf Stream and Caribbean Sea. Through 

 the kindness of Mr. Henry Lee I have lately had the opportunity 

 of examining the newly-started growth of the common Coral- 

 lines officinalis, but curious as its cellular development is, it is 



