(Thursday, July 23, 1874)
Herschel, A. S.
Vibrations of air produced by heat, pp. 233-235
Scientific serials, pp. 235-236
7i ' 23,, 1 88 74] NA TURE is found necessary to produce and to maintain then. Ill heat. harmoniconls the action is less simple, the alternations of pressure as well as the oscillations of the air determining the ad- 11iisslon of the entering puffs. To judge from the position in w'hih a singing-flame sounds best in a chemical harmonicon, a certain " lead hlike that used in admitting steam to the cylinder of a steam-engine is necessary for the flames to exert their ex- pansive force, the gas perhaps not instantly igniting on its emergence from the jet ; and this " lead " lthe mere oscillations of the surrounding air are unable to supply ; but in the position which the jet occupies in the tube, the air-pressures, which return at periods answering to a half stroke of the flame before the oscillations, precipitate its development and enable it to exert its pressures at the proper times. The proportion of lead given to the flame increases as it approaches the middle of the tube, where only the variations of pressure act upon it, while at the lower end of the tube it is commanded entirely' like the air-blast of an organ-pipe, by the oscillations of the air. It is perhaps thus that a wire-gauze flame burning at the foot of a lamp-glass sounds so vociferously, because stationaryalternations of pressure in the lower part of the tube cannot affect the transmission of gas through the gauze, while the extensive oscillations there produced have perfectly free action in extin- guishing and replenishing the flame. By using a piece of thin glass connecting-tube about 4 ft. long, held ver- tically over an unlighted Bunsen jet, on lighting the gas escaping at the top, and carefully raising the tube so as to allow the flame to descend very slowly, it may be made to pause in its descent at the successive ventral points corresponding to the har- monic divisions of the tube, sounding the note of the section of the tube above it as it comes to each point of rest. On lowering the tube it ascends, stopping and singing at some higher point of rest, depending apparently upon the less instantaneous infamma- bility of the gas. With some difficulty, and by shielding the lower end of the tube as much as possible from draughts, the flame was sometimes made to drop quickly within a few inches of the bottom of the tube, stopping always at the same place and sounding there for a moment the lowest note of the tube, when by the strength of its vibrations it was either rapidly extinguished, or else lighted the Bunsen lamp below. The notes sounded by these means were, however, not nearly so loud and effective as those obtained when the gas-flame was held at its stationary points by making it come to rest upon wire-gauze. I am indebted for almost all of the foregoing experiments to Mr. Haigh, who was very skilful in suggesting and devising modifications of them, leading to the immediate conclusions re- garding the mode of their production to which they appear most distinctly to conduct. Other occupations have hitherto prevented me from attempting to extend and to examine them as thoroughly as they seem to deserve; but the field of research presented by the study of harmonic flames does not yet appear to he nearly exhausted, and the repetition of the above experiments by others will perhaps throw more light upon the doubtful questions with which they are still to some extent surrounded, enabling, it may be, the many significant and easily-recognised features of singing flames to be produced with even more than their present ease and certainty. A. S. HERSCHIEL SCIENTIFIC SERIALS THE Ceoloe,ical Magazine, July.-In this number Mr. J. Croll commences an article On the physical cause of the submergence and emergence of land during the glacial epoch, which is to be continued. As far as it goes it is concerned with the conceptions we have of the thickness of continental ice. An attempt is made to estimate the thickness of the great antarctic ice-cap, about which "observation and experience to a great extent may be said to be a perfect blank." The condition of the interior of the antarctic continent is inferred from the little that we know of Greenland. The diameter of the ice-cal) being taken at 2,800, the thickness at the centre is given at the lowest at 6 miles, reckoning a quarter of a degree only as the slope of the upp)cr surface. Mr. Hopkins has recorded that he found one degree the least slope on which ice will move. Ani ice-cap of only 6 miles in thickness is to many an unfamiliar idea, and "few things," Mr. Croll writes, " have tended more to mislead geologists in the interpretation of glacial phenomena than inadequate conclep dlons regarding the magnitude at continental ice.' -The other original articles are On the dawn and development of life on the 235 earth, by If. Woodward, F. R. S. --Notes on carboniferous mojno. myaria, by R. Etheridge, jun.-T1he geology of the Nottingham district, by Rev. A. Irving. Therc are two letters on the glacia- tion of the south-west of England, by Dr. Mackintosh and II. B. WVoodward.-Mr. Mallet writes that he does not see how he can be charged with " inisapprehen(ling " Mr. Scrope in the discus. sion on the nature of volcanic heat, and asks that as he has reduced his own views to clear definition (Phil. Trans., vol. i. 187;,) Mr. Scrope will do the same. Bu/letin (le I'A1,Acadmie A(7e/.' (/tS Scidnces, &r., tie Re/hiq ue, No. 5.-M. Van 1'eneden contributes the first part (65 pp. in length) of a paper entitled " ( )n the original distinction between the testicle and the ovary; the sexual character of the two pri- morial layers of the embryo; the morphological hermaphrodism of an entire 'individual'; an essay on the theory of fecundation." The " essay " opens with an introduction in which reference is made to Huxley's first pointing out that the organism of Zoo- phytes, Medusidne, Polyps, Siphonophora and Hydroidexe con- sists essentially of two layers, endoderm and ectoderm, and also to other writers who have studied the relationships of endoderm and ectoderm in various aspects. The second part contains the history and bibliography of the subject, and the third (50 pp. long) describes the author's researches on Ifydractiniai ec/inala, made during a lengthened visit to Ostend. He first describes the characters which the male and female reproductive zooids have in common, and carefully details his methods of prepara- tion. The microscopic description of the female and then of the male zooids or gonosomes is given in much detail, illustrated by plates. He arrives at the following conclusions :-The ovaries are developed entirely from the epithelial layer of the endoderm. Up to the time of maturity they remain entirely surrounded by the elements of the endoderm. The testicle and spermatozoa are developed from the ectoderm. The female sporosacs contain rudimentary testicular organs, and male sporosacs a rudimentary ovary. From a sexual point of view the ectoderm and endoderm have an opposite signification. If it is true that special organs have resulted from specialisation of function following division of labour, then we must believe that originally the whole ecto- derm performed the male sexual function and the endoderm the female. The ectoderm is the animal and male layer, the endo- derm the vegetation and female. Fecundation consists in the union of an egg, the product of the endoderm, with the product of the ectoderm, which brings chemical compounds of " opposite polarity " into union. The new individual is formed at the in- stant the elements of " opposite polarity" unite just as a mole- cule of water is formed by the union of atoms of hydrogen and an atom of oxygen.-WI. Henry contributes papers on chloral and chlor-ethylic ethers, &c.-M. F. Plateau has sent in a com- munication on the digestion of insects, which is to be published in the memoirs. Bu/letin tie Az Socei.e d'Anth/ropoo-ie de Paris, t. vii.-In the seventh volume of this journal M. Hamy gives us the results of his examination of M. Janneau s officially conducted investigations into the anthropology of Cambodia. He begins by endeavour- ing to define the meaning attached to the three words, " Moi," " Kha," and "Penang," which have hitherto been used in Annamite, Laolian, and Kmer almost indiscriminately to indi- cate the wild tribes of the hills. By the first of these we must understand the negro tribes occupying the oriental chain of the Cambodian range; in the second a people not unlike the yellow races of Laos ; and in the third the tribes in whom the flat-faced non-Caucasian type is strongly marked. The Cambodians themselves distinguish between races, known as K u i, who, they say, are the primitive people of the land but not savages, and the Rode, the former being employed in the extraction of the ores of Kompong Svai, and the latter in the breeding, and care of horses, while both are exempt from the yoke of slaver- which presses leavily upon nearly all the other tribes. In the C ami;. bodian language Al. Janneau thinks he call trace evidence of identity with many of the piiimnitive forms of the roots of the mother-tongue of the I nmlo- 1Juropean languages. The Aryan name " Saina)" appears among the ancientt regal titlcs of ( aiblwdlia, and while the Sanscrit *" lRanlayana " includes the Cambudiamis amnongst the offsprimi, (tI the immaculate cow, ( abala, the people tbeniselvts lave 1- om the most remote antiquity made the towv the object of sccial aduration.-Tlhie S- tion of the depopul.tion of certain d1ish 1ci, Inure e>-c.i.dly in the Polynesian and othllr AustralAsiIn insular gioups, has lately attracted especial attention among the members of the Anthro- pological Society at Paris. 'Ihe Gambier Islands, which in of the 05c, 'e ati Ile tL-d ir Ot ,,p..- te ::s iot E:; It.Iai j jo 05C_ xr.,t frciz . '-Ai.:l'- anv , :~ oiiO ,w, e... tE -,>
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