Jan. 21, 1875] 



NATURE 



239 



Coggia's Comet presented in the spectroscope three distinct 

 spectra : — 



1. A continuous spectrum from the light of the nucleus. 



2. A spectrum of bright bands. 



3. A continuous spectrum accompanying the gaseous spectrum 

 on the coma, and representing almost entirely the light of the 

 tail. 



The author then gives his observations of three different 

 spectra, and of the relative iateusity of the two latter spectra 

 in different parts of the comet. 



On acoustic reversibility, by J. Tyndall, D.C.L., LL.D., 

 F.R. S. In this paner Prof. Tyndall refers to the series of 

 experiments on the velocity 01 sound which were made on the 

 2lst and 22nd of June, 1S22, between Villejuif and Montlhery, 

 south of Paris, and 1 1 '6 miles distant from each other. 



On this occasion it was noticed that while every report of the 

 cannon fired at Montlhery was heard with tlie greatest distinct- 

 ness at Villejuif, by far the greater number of the reports from 

 Villejuif failed to reach Montlhery. The air at the time was calm, 

 the slight motion of translation actually existing being from 

 Villejuif towards Montlhery, or against thetUrection in which the 

 sound was best heard. 



So far as the author knows, no explanation of this has hitherto 

 been given. 



Experimenting with a sensitive flame, from iS to 24 inches in 

 height, and a reed, less thanascuare quarter of an inch in area, 

 on a screen of cardboard, iS inches high by 12 inches wide, in all 

 dses it was shown that the sound was effective when the reed 

 was at a distance from the screen and the flame close behind it ; 

 while the action was insensible when these positions were re- 

 versed. 



It was observed and recorded when the experiments of 1822 

 were made, that while the reports of the guns ai Villejuif were 

 without echoes, a roll of echoes, lasting from twenty to twenty- 

 five seconds, accompanied every shot at Montlhery, being heard 

 by the observers there. 



From various considerations the author infers that Montlhery, 

 on the occasion referred to, must have been surrounded by a 

 highly diacoustic atmosphere ; while the shortness of the echoes 

 at Villejuif shows the atmosphere surrounding that station to 

 have been acoustically opaque. 



The non-homogeneous air surrounding Villejuif is experi- 

 mentally typified by the screen with the source of sound 

 close behind it ; the upper end of the screen representing the 

 place where equilibrium of temperature was established in the 

 atmosphere above the statioa. In virtue of its proximity to the 

 screen, the echoes from the sounding -reed would, in ths case here 

 supposed, so blend with the direct sound as to be practically 

 indistinguishable from it, as the echoes at Villejuif followed the 

 direct sound so hotly, and vanished so rapidly, that they escaped 

 observation. And as the sensitive flame, at a distance, failed to 

 be effected by the sounding body placed close behind the card- 

 board screen, so, the author takes it, did the observers at Montlhery 

 fail to hear the sounds of the Villejuif gun. 



Something further may be done towards the experimental 

 elucidation of this subject. The facility with which sounds pass 

 through textile fabrics has been already illustrated ; " a layer of 

 cambric, or even of thick flannel or baize, being found competent 

 to intercept but a fraction of the sound from a vibrating reed. 

 .Such a layer of cambric may be taken to represent a layer of air 

 differentiated from its neighbours by temperature or moisture ; 

 while a succession of such sheets of cambric may be taken to 

 represent successive layers of non-homogeneous air. 



Two tin tubes with open ends were placed so as to form an 

 acute angle with each other. At the end of one is the vibrating 

 reed ; opposite the end of the other, and in the prolongation of 

 its axis, is a sensitive flame — a second sensitive flame being 

 placed in the continuation of the axis of the first tube. On 

 sounding the reed, the direct sound through the first tube 

 agitates the second flame. Introducing the square of cambric at 

 the proper angle, a slight decrease of the action en the second is 

 noticed, and the feeble echo from the cambric produces a barely 

 perceptible agitation of the first flame. Addirg another square, 

 the sound transmitted by the first square impisiges on the second. 

 It is partially echoed, returns through the first square, passes 

 along the second tube, and still further agitates the flame oppo- 

 site its end. Adding a third square, the reflected sound is still 

 iuither augmented, .every accession to the echo being accom- 



* Pliil, Trans., Feb. 1874. 



panied by a corresponding withdrawal of the vibrations from the 

 flame opposite the first tube, and a consequent stilling of that flame. 

 With thinner cambric it would require a greater number of 

 layers to intercept the entire sound. Hence, with such cambric 

 we should have echoes returned from a greater distance, and' 

 theicfore, of greater duration, ' 



Jan. 14.—" On a Class of Identical Relations in the Theory 

 of Elliptic Functions," by J. W. L. Glaisher, M.A., Fellow of 

 Trinity College, Cambridge!; communicated by Tames Glaisher, 

 F.R.S. 



Chemical Society, Jan. 14. — Prof. Odiing, F.R.S., presi- 

 dent, in the chair. — On the action of the organic acids and their 

 anhydrides on the natural alkaloids. Part III., by Mr. G. PI. 

 Beckett and Dr. C. R. A. Wright, was read by the latter. It is 

 a continuation of their researches on the opium alkaloids mor- 

 phine and codeine. — The next communication was a note on the 

 effect of passing the mixed vapours of carbon bisulohide and 

 alcohol over red-hot'copper, by Mr. T. CarneUy. — Dr. H. E, 

 Armstrong then read a paper on the iodonitrophenols. 



Anthropological Institute, Jan. 12.— Prof. Busk, F.R.S., 

 president, in the chair.— Mr. T. J. Hutchinson, F.R.G.S., late 

 H.M.'s Consul, Callao, read a paper on the anthropology of 

 Prehistoric Peru. The paper commenced with a notice of how 

 little is known up to the present time about the glorious days of 

 Peru long before the time of the Incas, agreeing with Mr. 

 Baldwm as to the original South Americans being the oldest 

 people on that continent. The grandeur of colossal works in the 

 extent of the ancient burial mounds was shown bv illustrations. 

 A comparison of these examined by the author in Peru was made 

 with those explored by Messrs. Squier and Davis in the valleys 

 of the Ohio and the Mississippi. The prehistoric architecture of 

 Peru, described by Prof. Raimondi in his recent work on the 

 mineral riches of the department of Aucachs, were mentioned as 

 highly interesting ; more particularly the tombs cut out of solid 

 blocks of diorite in the valleys where sandstone is the geological 

 character ; thus proving the enormous capacity for work of the 

 ancient Peruvians in transporting these stony masses over the 

 Andes. So small was the author's faith in Spanish accounts of 

 South America, that he inclined to the belief in some future 

 explorer finding the mythical ''cradle of the Incas" in the 

 National Library at Madrid, instead of in the Lake of Titicaca, 

 to which latter place it is accredited by the Hakluyt Society. — 

 A paper, by Dr. George Dobson, was read on the Andamans 

 and Andamanese. After givmg a sketch of the geographical 

 position of the Andaman Islands and their geological and zoolo- 

 gical relations to the ."Asiatic continent, the author passed in 

 review the various theories that had been propounded by eminent 

 biologists to account for the origin of the Andamanese. He 

 strongly inclined to the views of Mr. Wallace and M. Quatre- 

 fages that the Andamanese are Nigritos, or Samangs from the 

 Malay peninsula, and was opposed to the theory of their descent 

 from shipwrecked African negroes, on the ground rather of the 

 dissimilarity of their maimers and customs than of their physical 

 characteristics. It was impossible, however, to account for the 

 presence of the wild tribes of Southern India or of the peculiar 

 Samangs of the interior of the Malay peninsula, surrounded by 

 races with which they have no connection whatever, except on 

 the hypothesis that they are the few surviving descendants of a 

 woolly-haired people which in ages past occupied lands south of 

 the Ilimalayas when the continent of Asia included within its 

 southern limits the Andamans, Nicobars, Sumatra, Java, Borneo, 

 ,nnd the Philippine Islands ; and that the present inhabitants of 

 the Andamans and the Nigritos of the Philippines are also the 

 remnant of those ancient Nigrito inhabitants of Southern Asia, 

 which have almost disappeared belore the invaduig Aryan and 

 IVi ongolian races. Dr. Dobson exhibited a series of photographs, 

 taken by hinrself, of Andamanese men and women. 



Entomological Society, Jan. 4. — Sir Sidney Smith Saun- 

 ders, C.M.G., president, in the chair. — Mr. Stevens exhibited 

 varieties of Diloba cicrukocefhala and llibciuia dcfoliaria, bred 

 from larviE taken near Brighton. — Mr. Smith exhibited a box of 

 hymenopterous insects collected in the neighbourhood of Cal- 

 cutta by Mr. Rothney. It comprised several rare species of 

 loiiiiicidit and Fosicics, and also many undescribed species of 

 Aptdcc, amongst which were two species of Noniia, one of them 

 with remarkable capitate antenna;. — Mr. M'Lachlan made some 

 remarks on the December Moth (Cheimaiobia brumaia), which 

 ho had observed one evening during the recent severe frost 



