3^4 



NATURE 



{March 14, 1878 



Placide, of St. Amour, and Crispinien, of Toulon, and by 

 the two Brothers Bonaventura and Gregory, all of the 

 Order of St. Francis. Father Gregory, it is said, was 

 the celebrated Lyonnaise geogranher, Henry Marchand. 

 In speaking of these discoveries at the Paris Geographical 

 Society, M. R. Cortambert showed that there was nothing 

 extraordinary in them. From the fifteenth century most 

 of the maos make the Congo issue from a great mass of 

 water in the interior of the African continent. No doubt 

 all the information in these old maps was furnished by 

 the Portuguese. M. Vivien de St. Martin is also of this 

 opinion. The Portuguese traders were quite au coura7it 

 with the geography of the interior of Africa, and all the 

 maps, even that of Fra Mauro (15th century) represent 

 the Nile issuing from lakes to the south of the equator, 

 and give an idea of the course of the Congo, similar to 

 that made known by Stanley. M. St. Martin reminded 

 the Society, moreover, that Ptolemy himself had indicated 

 three immense lakes in the centre of Africa from which 

 issued the Nile and the Congo ; only in his map these 

 lakes are placed much too far south. Father Kircher, in 

 his " Mundus Subterraneus," published at Amsterdam in 

 1653, gives a map showing four large lakes, from one of 

 which, called Zaire, both the Nile and the Congo are 

 made to issue. Krcher states that he obtained his 

 information from the General Procurator of the Jesuits for 

 these provinces, who lent him a manuscript of Father 

 Pais. Thi"! manuscript may possibly be still preserved in 

 the Jesuit College at Rome. 



Paris Geographtcal Society.— Besides the medals 

 to Mr. Stanley and M. St. Martin, the Paris Geographical 

 Society will give medals to Dr. Harmand for his explor- 

 ation of ihe Mekong and the coast of Anam, and to M. 

 Ujfalvy for his travels in Turkestan. The Btdletin for 

 December contains an important geographical and sta- 

 tistical article on Kashgar, compiled from various sources 

 bv M. J B Paquier, an itinerary on the Yang-tsze from 

 Shun^'-shing to Yun-nan-fu, by M. Rocher, and a valuable 

 summary of the geodetic work of the Russian Geographi- 

 cal Society in Asia, by Col. Chanoine. 



NOTE ON THE DISCOVERY OF THE LIQUE- 

 FACTION OF AIR AND OF THE SO-CALLED 

 PERMANENT GASES 



TN the Notes on " Recent Science," in this month's 

 Ninfteenth Century, the writer, in an account of the 

 results of the researches of M. Pictet and M. Cailletet on 

 the condensation of the so-called permanent gases, draws 

 .•ittention to the lone-neglected paper of Mr. Perkins 

 " On the Compressibility of Water, Air, and other Fluids," 

 an abstract of which, and apparently the only one with 

 which the writer is acquainted, appeared in Thomson's 

 Annals of Philosophy, N. S., vol. vi., 1823. The paper 

 was intended for the Royal Society, but, being mislaid, 

 was not read at the appointed time. Either it or a second 

 paper was, however, brought before the society on June 

 15, 1826, and appears in the Philosophical Transactions 

 for that year. In this paper, as in the brief record in 

 the Annals, Mr. Perkins announces that he had efifected 

 the liquefaction of atmospheric air, and other gases, by 

 a prc-ssure of upwards of 1,000 atmospheres, and fully 

 describes the apparatus which he. had employed, which 

 is, in principle, very similar to that of M. Cailietet. 

 He ihus describes his results in the case of aeriform 

 fluids : — 



" in the course of my experiments on the compression 

 of atmospheric air by the same apparatus which had been 

 used for compressing water, I observed a curious fact 

 which induced me to extend the experiment, viz., that of 

 the air beginning to disappear at a pressure of 500 atmo- 

 spheres, evidently by partial liquefaction, which is indi- 

 cated by the quicksilver not settling down to a level with 

 its surface. At an increased pressure of 600 atmospheres, 



the quicksilver was suspended about |th of the volume up 

 the tube or gasometer ; at 800 atmospheres it remained 

 about \ up the tube ; at 1,000 atmospheres, | up the tube ; 

 and small globules of liquid began to form about the top 

 of it ; at 1,200 atmospheres the quicksilver remained | up 

 the tube, and a beautiful transparent liquid was seen en 

 the surface of the quicksilver, in quantity about go'biT P^-''^ 

 of the column of air. On another occasion a second tube 

 was charged with ' carburetted hydrogen ' and subjected 

 to pressure ; it began to liquefy at about 40 atmospheres, 

 and at 1,200 atmospheres the whole was liquefied." 



Mr. Perkins goes on to say : '* These instances of 

 apparent condensation of gaseous fluids were first ob- 

 served in January, 1822, but for want of chemical know- 

 ledge requisite to ascertain the exact nature of the liquids 

 produced, I did not pursue the inquiry further ; and 

 as the subject has been taken up by those who are 

 eminently qualified for the investigation, I need not regret 

 my inability to make full advantage of the power I had 

 the means of applying." 



Mr. Perkins's observations seem to have attracted little 

 attention at the time they were published, and have since 

 been, apparently, almost forgotten. Although they do not 

 in the least detract from the great merit of M. Cailletet's 

 work, they undoubtedly have their place in the history of 

 this subject of the liquefaction of the gases. 



It may be worth while to point out that the statement 

 that all the gases known to the chemist have now been 

 liquefied is not strictly true. The most recently-disco- 

 vered of these — phosphorus pentaflaoride — has not yet 

 been seen in the liquid state, although there is not the 

 least reason for believing that it will constitute an excep- 

 tion to the general law. T. E. Thorpe 



HELMHOLTZ'S VOWEL THEORY AND THE 

 PHONOGRAPH 



THE following experiments with the phonograph are of 

 interest as throwing light on the nature of vowel 

 sounds : — 



Let a set of vowel sounds, as A, E, I, O, U (pronounced 

 in Italian fashion) be spoken to the phonograph in any 

 pitch, and with the barrel of the instrument turned at a 

 definite rate. Then let the phonograph be made to speak 

 them, first at the same rate, and then at a much higher or 

 lower speed. The pitch is, of course, altered, but the 

 vowel sounds retain their qulality when the barrel of the 

 phonograph is turned at very different rates. We have 

 made this experiment at speeds varying from about three 

 to one, and we can detect no ■ alteration in the quality of 

 the sounds. 



According to Helmholtz, the characteristic quality of 

 each vowel is given by the prominence of a constituent 

 note or notes, of dt finite or approximately definite absolute 

 pitch, in the sounds uttered. Now obviously, the absolute 

 pitches of the constituents of the vowel-sounds in the 

 above experiment were all altered in the same proportion, 

 so that the absolute pitch of the prominent notes varied 

 greatly ; but yet the vowel quality was unchanged. This 

 experiment, therefore, appears to give results in contradic- 

 tion of Helmholtz's theory as we understand it. 



At the same time we have found, in the course of 

 experiments, of which a full account will shortly be com- 

 municated to the Royal Society of Edinburgh, that if a 

 scale be sung to the phonograph with one vowel sound, 

 such as O, the wave-form of the marks on the tinfoil does 

 not remain unchanged at all pitches. We have not yet 

 had time to analyse the curves so obtained into their 

 harmonic constituents. Such an analysis will show 

 whether the changes we have observed in the wave-form 

 as the pitch rises, are due to a change in the relation of 

 the amplitudes of the constituents present, or only to a 

 variation -of phase. Fleeming Jenkin 



Edinburgh, March 11 J. A. EwiNG 



