278 



NATURE 



{July 20, 1882 



origin, or with phase difference = o. If the slit be in- sponding to phase-difference = \. It is easy then to 

 clined in the opposite direction the quality is that corre- examine whether or not the effect of these differences of 



^Mll 



Fig. 8.— Position of the slits for phase-difference o. 



phase on the ear is the same, by merely inclining the 

 slit forward or backward. Kcenig finds invariably a purer 

 and more perfect sound with phase-difference = o, and a 





Fig. 9.— Position of the slits for phase-difference J. 



more strident and nasal sound with phase-difference = \. 

 This result is so easy to verify that it will doubtless be 

 tried by many experimenters. Indeed many of the re- 



searches with the wave-disks are so easily repeated with- 

 out any special or expensive apparatus that they will 



Effect of inclining the slil 



surely win a place amongst the familiar experiments ot 

 acoustics. S. P. T. 



HONOUR TO M, PASTEUR 



A T the seance of the Paris Academy of Sciences on 

 ■**- the 26th ult., the President (M. Jamin) stated that 

 a gathering of savants, friends, and admirers of M. 

 Pasteur having resolved to present him with a medal 

 commemorative of his remarkable discoveries, a com- 

 mittee had been appointed to watch the execution of it. 

 On completion of the work, this committee, on June 25, 

 repaired to M. Pasteur's house to present the medal, 

 which is the design of M. Alphee Dubois, and happily 

 recalls the physiognomy of its distinguished recipient. 

 The meeting included MM. Dumas, Boussingault, Bouley, 

 Jamin, Bertin, Tisserand, Davaine, and others. On this 

 occasion M. Dumas delivered an address, in which he 

 recalled the labours of M. Pasteur ; and after receiving 

 the medal, M. Pasteur made a few observations in reply. 

 The two speeches have been, on the suggestion of M. 

 Thenard, inserted in Comptes rendus, and we here repro- 

 duce them, in translation. M. Dumas said : — 



" My dear Pasteur, — Forty years ago you entered 

 this house as a student. From the first your teachers 

 foresaw that you would be an honour to them ; but none 

 would have ventured to predict what brilliant services 

 you were destined to render to science, to the country, 

 and to the world. 



" Your earliest labours banished occult forces for ever 

 from the domain of chemistry, by explaining the anoma- 

 lies of tartaric acid. 



"Confirming the vital doctrine of alcoholic fermenta- 

 tion, you extended this doctrine of French chemistry to 

 the most diverse fermentations, and you gave to the manu- 



facture of vinegar, rules which industry now applies with 

 thankfulness. 



"Among these infinitely minute living things you dis- 

 covered a third kingdom, to which those beings belong 

 which, with all the prerogatives of animal life, do not need 

 air to live, and which find the heat they require in the 

 chemical decompositions they excite around themselves. 



" The profound study of ferments gave you the com- 

 plete explanation of alterations undergone by organic 

 substances — wine, beer, fruits, animal matters of all kinds ; 

 you explained the preservative rdle of heat applied to 

 their conservation, and you learned to regulate the effects 

 of it according to the temperature necessary to cause the 

 death of ferments. Ferments when dead produce ferments 

 no more. 



" It was thus that you were led to maintain throughout 

 the extent of the organic kingdoms the fundamental 

 principle according to which life is derived from life, and 

 which rejects as a useless and unfounded supposition the 

 doctrine of spontaneous generation. 



" It is thus that, showing air to be the vehicle of the 

 germs of most ferments, you learned to preserve with- 

 out alteration the most putrescible matters, by keeping 

 them from all contact with impure air. 



"Applying this idea to the alterations, so often fatal, 

 to which wounds and sores are liable when the patients 

 inhabit a contaminated place, you learned to guard them 

 from this danger by surrounding their limbs with filtered 

 air, and your precepts, adopted by surgical practice, daily 

 insure to it successes it knew not before, and give its 

 operations a boldness of which our predecessors had no 

 presentiment. 



