342 



NA TURE 



\Feb. 29, 1872 



be distinguished amid the black mass that surrounded 

 them ; the lines near C and C or y of Brewster were 

 sharp and clear. 



On nearing India another change took place ; the blue 

 continued to be absorbed, till at sunrise the spectrum 

 could hardly be seen beyond F, but the blue green became 

 very bright, and the dark bands between b and F very 

 distinct, the lines commencing at 1S25 Kirchhoff especially 

 attracted notice, standing out sharp and distinct, so as at 

 first to be mistaken for F : those nearer F at 1S90 K 

 showed as a clear broad band, but not nearly so black as 

 1825. I am not prepared to give an explanation of this 

 phenomenon, but will remark that when the sun rose clear 

 and free from clouds the aqueous bands to D were less 

 distinct, while the atmospheric bands from D to E were 

 clear and sharp, and those beyond b remarkably so. But 

 if the sun rose among clouds, these were generally 

 tinted with a golden yellow, changing afterwards to arose 

 or red colour, and, as might be expected, the lines from 

 B to D and just beyond D, were well defined, whilst from 

 E to near F the spectrum was not so clear. 



After this the duties of preparing the instruments for 

 the eclipse prevented my taking any observations, as most 

 of our work was done in the early morning. But after 

 the eclipse, whilst on the Neilgherry Hills, 6,000 feet above 

 the sea, I had an opportunity of finding that the strong 

 hne at 1S25 had nearly faded away. The v.'eather was 

 then fine, but misty. A few days after, on going down 

 the Ghauts to Bombay, I was struck with the blue colour 

 of the mist that was hanging about the valleys, and I ex- 

 amined it with the spectroscope ; the blue extended much 

 farther than usual, and the lines between b and F were 

 again distinct. 



On the passage home the same results were obtained 

 as on going out ; but as I had a much smaller spectro- 

 scope I could not make the observations with the same 

 accuracy as before. When passing up the Red Sea the 

 absorption was evident at both ends of the spectrum, and 

 the mountains were of the same beautiful purple colour 

 that I had noticed before. 



From Alexandria to Southampton we had very bad 

 weather, constant gales, making it difficult to observe. 

 But I got the following results : With a cloudy sky at 

 sunrise, and appearance of wet weather, the bands from 

 B to beyond D (8 of Brewster) were strong, whilst the 

 blue end of the spectrum was greatly absorbed, and the 

 lines from /' to F were less distinct ; this was reversed 

 with clear weather. As we gained higher latitudes, the 

 blue end of the spectrum lengthened out, and the bands 

 beyond F, particularly about 2330 K, became distinct, 

 while the bands 1825 K and 1890 K gradually faded, 

 and now their intensity is not one-fourth of what I 

 observed it in the Indian Ocean. 



These observations are very imperfect, but 1 hope, if I 

 can get the instruments, to carry out a more perfect system 

 of observation, feeling sure that it is a subject worthy of 

 great consideration in meteorology, especially when taken 

 in connection with the temperature and pressure of the 

 atmosphere and the state of the weather. 



Shanklin, Feb. 5 J. P. Maclear 



PROF. AGASSJZ'S EXPEDITION 



IT is probable that I may have been anticipated, as 

 regards part of the present communication. If not, 

 I believe that many of your readers will be glad to learn 

 the objects with which Prof Agassiz has started, with 

 Count Pourtales and a distinguished band of skilled ob- 

 servers, on a scientific expedition in the United States' 

 surveying ship Hassle?-, and to receive a brief account of 

 what he has already done at St. Thomas and Barbados, 



at which places he was obliged to touch, in consequence 

 of defects in the vessel or her machinery. 



The Professors chief objects are stated in a letter from 

 himself to Prof Peirce, the Superintendent of the U.S. 

 Coast Survey. (See Nature, vol. V., p. 194.) 



The Expedition was detained some days at St. Thoma?, 

 andthetime of the Professor and his assistants was devoted 

 chiefly to the collection and preparation of fishes, with a 

 view to the study of the brain, and the breathing and di- 

 gestive organs. Several boxes full, preserved in alcohol, 

 were at once shipped to the United States, as the first- 

 fruits of the Expedition. 



The party arrived at Barbados on December 26, and 

 spent four days there. The first two were devoted by the 

 Professor to examining and studying the large collection of 

 West Indian shells, marine and terrestrial, of corals, 

 sponges, Crustacea, and semi-fossil shells of the island, 

 made by the Governor, Mr. Rawson. Of the marine 

 series he wrote in the following terms to Mr. J. G. 

 Anthony, the Curator of the Harvard Museum : — " I am 

 having high carnival. I have found here what I did not 

 expect to find anywhere in the world — a 'collection of 

 shells in which the young are put up with as much caic 

 as the adult, and extensive series of specimens show the 

 whole range of changes of the species, from the formation 

 of the nucleus to the adult." He was particularly struck 

 with the now unique specimen of Holopiis, lately pro- 

 cured by Mr. Rawson, which was described by Dr. J. E. 

 Gray in the December number of the " Annals of Natural 

 History," and named by him, from a drawing, //. Rawsoni, 

 but which Agassiz, who had seen the specimen of 

 D'Orbigny in Paris, before it disappeared, considers to 

 be a normal specimen of H. Ranzii, which had only four, 

 instead of five arms. Count Pourtales recognised among 

 the corals several similar to those which he had obtained 

 by dredging in or near the Gulf Stream, and described 

 in the latest No. (4) of the " Illustrated Catalogue of the 

 Museum of Comparative Zoology at Harvard College,' 

 the presence of which on the coast of Barbados serves to 

 indicate the close similarity of submarine life in those 

 two distant localities. 



The next two days, or rather the night of the next, and 

 the greater part of the following day, were spent in dredg- 

 ing in the neighbourhood, in a depth of 60 to 1 20 fiithom's, 

 about a mile from the shore, whence Mr. Rawson has 

 procured his fine specimens of Peiitcioiinis Miilleri. 

 The Holopiis was found on the opposiie side of the island. 

 The results were beyond the expectations, or even the 

 hopes, of the most sanguine of the party. Only dead 

 fragments of the Pentaciiims were obtained, but among 

 the abundant spoils were four specimens of a new genus 

 of Crinoid, without arms on the iX.tiWffyik^ Rhizoainiis :') 

 which remained alive, with the arms in motion, until 

 noon on the following day, under the excited observation 

 of the party. A number of deep-sea corals, alive, Crus- 

 tacea, sea urchins of new species, star fish, sponges, crys- 

 talline, Jurassic, and corallines, &c., and a rich harvest of 

 shells, were obtained. Amongthese was a splendid live spe- 

 cimen of /'/(7i';<?/ow);<7Vi Ouoyana, F and B, of which genus 

 Chenu writes that only one living species, and of that only 

 one specimen, is known. The animal exhibited re- 

 markable affinities, and the artist accompanying the ex- 

 pedition was able to take several sketches of it. A large 

 Oniscla, shaped like O. caiicellata Sow. but with an 

 orange inner lip {O. Dennlsoiii ?), some specimens of 

 Plioius Indicus Gmel., a magnificent new species of 

 Lni/nxis, with many exquisite specimens of Plairoloiita, 

 Fitsns, Murex, ^calaria, and three or four of Pcdicularia 

 siciila Sw., with innumerable Pteropods and Terebratu- 

 lina:, rewarded these '" burglars of the deep." The Pro- 

 fessor was deligh'ed, and it was with reluctance he 

 abandoned so rich a field in order to Secure his passing 

 through the Straits of Magellan at a right season. 



Barbados, January 26 " R. W, R, 



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