November 8, 1894] 



NA TURE 



LETTERS TO THE EDITOR. 



[The Editor does not hold himselj responsible for opinions ex- 

 pressed by his correspondents. Neither can he undertake 

 to return, or to correspond with the writers oj, rejected 

 manuscripts intended for this or any other part of Nature. 

 No notice is taken of anonymous communications.'^ 



Prof. Boltzmann and the Kinetic Theory of Gases. 



In the discussion wtiich followed the communication of my 

 Report on Thermodynamics to the British Association at 

 Oxford this year, Prof. Boltzmann made some remarks which 

 appear to have been interpreted in a different light to what he 

 doubtless intended. In the absence of any shorthand writer's 

 verbatim report of the discussion, it is of course impossible 

 to recall his exact words, but I feel sure that Prof. Boltz- 

 mann will be much astonished to learn that his statements are 

 now widely circulated and quoted as being an authoritative 

 admission that the Kinetic Theory of Gases is nothing more 

 than a purely mathematical investigation, the results of which 

 are not in accord with physical phenomena ; in short, a mere 

 useless mathematical plaything. 



Is it likely that such an able physicist would have de- 

 voted so many years to the development of the theory, and 

 would continue to work at it now if he regarded it in that light ? 

 Having had several conversations with him, both during and 

 after the British Association meeting, I gather that his views 

 are not nearly so pessimistic as the opponents of the kinetic 

 theory would wish to maintain. 



The slalements were made in reply to a question as to how 

 far the ratios of the specific heats of gases as given by theory 

 accorded with the lesulls of e.xperinient. What I understood 

 Prof. Boltzmann to imply was that his investigations treated 

 the matter purely from a mathematical standpoint, but that the 

 values he obtained by regarding the molecules of a gas as rigid 

 bodies, viz. I '6 for smooth spheres, i'4 for smooth solids of 

 revolution, and I '3 for solids of any other form, accorded on 

 the whole rery fairly with the results of experiment. In that 

 respect the kinetic theory stands on exactly the same footing 

 as any other theory of mathematical physics. The evidence in 

 fa\our of the fundamental assumptions of any theory 

 necessarily rests on the agreement or want of agreement of 

 the deduction! with experience after due allowance is made 

 for the iact that the conditions imposed by the mathematical 

 difticuliies of the investigation necessarily differ from those 

 occurring in nature. I need only refer ro Prof. Boltzmann's 

 paper. " Ueber die Natur der Gasmolekiile" {Silziiitgsbciichte 

 dcr Wiener Akaacntie, Ixxiv. ii. 1876), for a more detailed 

 account of his views on the question of the specific heats. 



The objection which has been regarded by some as most 

 antagonistic to the kinetic theory is that it does not afford an 

 expl.ination of the spectra of gases. But is this duty required 

 of it ? If the luminosity of gases were due to vibrations of 

 the atoms in the molecules, certainly there would be a difficulty 

 about regarding the molecules as rigid bodies ; but then such a 

 hypothesis would preclude a gas whose molecules were 

 monatomic from having any optical properties whatever. To 

 my mind, the electromagnetic theory of light entirely relieves 

 the kinetic theory from the burden which has been imposed 

 on it by its opponents, since it (for example) we regard the 

 molecules of a gas as perfectly conducting hard spheres, 

 spheroids, or other bodies moving about in a dielectric 

 "vacuum" {i.e. space devoid of ordinary matter), we shall be 

 able to account for the spectra by means of electromagnetic 

 oscillations determined by surface-harmonics of different orders 

 without interfering with the assumptions required for explain- 

 ing the specific heats of gases. There are, however, other 

 questions on which I should bi glad to see a continuation of 

 the brilliant discussion which had to be curtailed from want 

 of time at Oxford. G. II. Brvan. 



Pelerhouse, Cambridge, October 23, 



Instinctive Attitudes. 



Mv attention has been called to Mr. M. M. Stanley's remarks 

 on instinctive altitudes in Nature of Oct. 18. I have been 

 for some years studying children's attitudes and expressions from 

 the eioluiion point of view ; and have from time to time taken 

 pholographi as opportunity presented itself. I have now a 

 considerable number which I hope to publish in that connection. 



NO. 1306, VOL. 5 I J 



One of the series accompanies this, and bears on Mr. Stanley's 

 remarks. It was taken in M.iy last, representing my youngest 

 child, then ten months old. She never crawled, but always pro. 

 gressed on all-fours ; and this photograph, taken instantaneously, 

 shows her mode of travel to and fro on the garden path. The 

 interesting thing about it is this : that the gait is front and 

 back legs on opposite sides, like a dog or a cat, not on the same 

 side, like a camel — a result which the evolutionist would have 

 predicted ; though of course we show a relic of the same habit 

 in walking, by swinging the arm on the opposite, and not on the 

 same, side as the leg. In this photograph, too, the heel and 

 toe action of the hind limbs is instructive. 



One of my children, in addition to the ordinary crawl, used to 

 progress in a sort of three-legged fashion — it used the left hand 



and the right foot for the forward step, rested itself on the 

 shank of the left leg tucked under its body, and this it used as 

 a foot to bring forward its body for the next step. Sometimes 

 this developed into a three-step mode of progression. 



The bandaging, swaddling, carrying and wheeling about, which 

 the civilised infant has suffered for many generations, no doubt 

 partly accounts for the rarity of the quadrupedal mode of pro- 

 gression, by having hindered development of muscularity. The 

 quadrupedal mode of progression indicates greater strength than 

 the ordinary knee-crawl. S. S. BucKMAX. 



Cheltenham, October 24. 



James Parkinson, the Author of " Organic Remains 

 of a Former World." 



Ln' a paper on the subject of museums, » hich was read in 

 1891 be/ore the meeting of an association, James Parkinson is 

 thus spoken of without any subsequent qualification of the state- 

 ment made : — 



" Finally, a private lottery was arranged for its disposal (the 

 Leverian Museum), and in 17S5 the prize was drawn by James 

 Parkinson, a dentist, who took not the least interest in natural 

 history or in museums." 



As the scientific world seems profoundly ignorant as to what 

 were the scientific qualifications and professional position of 

 James Parkinson, the following facts may be worth publishing 

 in Nature : — 



James Parkinson, who resided at No. I Hoxton Square, was 

 not a dentist, but a surgeon. ■ In Johnston's Directory for 18 17 

 his address is thus given ; " Parkinson and Son, Surgeons, 

 No. I Hoxton Square." He had also an address in the Kings- 

 land Road. His death is thus recorded in the Gentleman s 

 Magazine of December 1824: " DeceUiber 21st, in Kingsland 

 Road, James Parkinson, surgeon, late of Hoxton Square." 

 There u\is a firm of dentists in London, whose address in John- 

 ston's Directory was as follows: — "Paikin-on and Kidman, 

 surgeon-dentists, i Racquet Court, Fleet Street " ; but they had 

 evidently no professional connection with James Parkinson. 



The following list of works, &c., by James Parkinson, pub- 

 lished by H. I). Symonils, Paternoster Row, is giveii at the 

 end of a little book by him, of which the title is " Dangerous 

 Sports ; a Tale addressed to Children," printed for H. D. 



