ISO 



KNOWLEDGE. 



[August, 1903. 



for oach one, tbc j)lan is necessary, aud natiirally suggests 

 itself as likely to facilitate tlie easy retention of our know- 

 ledge of (li^tail. The method is certainly not perfect in its 

 application to all the facts accnniulated. For instance, 

 spots have temporarily appeared in the north-temperate 

 region with a rotation of only 9h. 48m., yet the normal 

 rate of this latitude is 9h. 55m. 55s., and represents 

 the slowest current of all. But the i-apidly-moving 

 spots alluded to formed a very exceptional incident, and 

 should not be allowed to negative a system which has 

 much to recommend it. 



Occasionally there are seen markings on Jupiter of a 

 very curious and special description, and apparently dis- 

 similar to all the rest. These are in the form of faint dusky 

 streaks, running from spots on the north-temperate belts 

 to the region of the north pole. They cross the belts at 

 right angles, and one of these features— the centre of three 

 — was very conspicuous on July 1, 1903, in longitude 13°, 

 and in transit at approximately the same time as the 

 preceding end of the great red spot. The aspect of these 

 northern latitudinal spots was somewhat as under : — 



151i. 36m. 161i. 12m. 



Northern Hemisphere of Jupiter, July 1. 



10-in. Reflector, power 312. 



They are not often visible, and I am not aware who was 

 the first discoverer of markings of this kind, but they are 

 certainly of a distinctive and interesting character, and 

 deserve more attention than they have hitherto received. 

 I must confess, however, that I cannot altogether do away 

 with the impression that they are an optical illusion. 

 The spots to which these polar streams are attached are 

 located in a latitude which is rather productive of dis- 

 cordant phenomena, and often displays a considerable 

 amount of activity. Tt is in this north-temperate region 

 of Jupiter that the swiftest and the slowest spot-motions 

 have been detei-mined, and these and other anomalies 

 present a strange contrast to the behaviour of the south- 

 temperate lielt, which has preserved a very equable 

 rate of about 9h. 55m. 18-7s. during many years. 



Accompanying this paper are four representations of 

 Jupiter — copied from drawings made at the telescope — 

 and they will siifficiently illustrate the general aspect of 

 the planet in July, 1902, and June, 1903, without pre- 

 Bimiing to critical exactness as to the positions in latitude. 



Hetttrs. 



[The Editors do not hold themselves responsible for the opinions 

 or statements of correspondents.] 



"MOLECULES AND HEAT." 



TO THE EDITOES OF KNOWLEDGE. 



Sirs, — I would like to say a few words upon Mr. Edser's 

 most fair criticism* upon my work on " Molecules and 

 Heat." Writing upon the theory my experiments have 

 suggested — I think proved — he states, " Such a theory 



* Knowledge, 1903, page 160. 



labours under all the difficulties that beset the old caloric 

 theory." There is a great difference between this new 

 theory and the old caloric theory. My view is that the 

 molecule is not a constant in dimensions. The old caloric 

 and the kinetic theories regard the molecule as constant 

 in dimensions. The fundamental fact — the all-important 

 fact to be explained is : eliminating the change of state in 

 the molecule — crystallization — any theory must explain 

 why matter, especially liquid and gaseous matter, becomes 

 lighter as it increases in temperature — for instance, hot 

 water floats upon cold water. Now, my view explains this, 

 but no other theory does. 



Physical science is full of what appear to me to be con- 

 tradictious in terms, which are believed in by men who 

 carry my highest esteem. Speaking of the objects — 

 spheres — I have shown floating in air, Mr. Edser says, " The 

 accepted explanation of this depends on the fact that a 

 gas or liquid exerts considerable friction on very small 

 particles, which are thus unable to sink quickly." This I 

 understand to mean, that there is contact between the gas 

 or liquid molecules and these small particles to produce 

 friction. Then he goes on to say, "The flask is filled with 

 aqueous vapour, the invisible small molecules of which are 

 comparatively widely separated from each other." A little 

 thought will show that these two statements are a con- 

 tradiction in terms. Now the views I have shown (wliich 

 are derived wholly from experiment) give the friction Mr. 

 Edser properly wants to import, and no other view does 

 this. Then he repeats the wide-spread error, that the 

 particles of dust in the air are centres of condensation, 

 producing " small water droplets." Quite forgetting that 

 experiment shows that such droplets gravitate, whereas the 

 objects I have shown him rise from the liquid — in fact, 

 dart off the liquid. To complete Mr. Edser's idea, we 

 should see raindi-ops jumping up from the pavements and 

 ascending to the skies, but who has ever seen such a 

 phenomenon ? Besides, I have shown experimentally that 

 the particles of dust in the air are not the factors in con- 

 densation, for we obtain condensation without these motes, 

 and with a single element, say, oxygen gas. Then Mr. 

 Edser objects to the concept that " a water molecule as a 

 spherical body composed of a great number of atoms of 

 oxygen and hydrogen, in the proportion of one of the 

 former to two of the latter," but goes on to say that this 

 molecule consists of " one atom of oxygen and two atoms 

 of hydrogen." Where is his authority for such a state- 

 ment y He will reply that he obtains it from the chemist. 

 But where is the chemist's authority ? Absolutely ha has 

 no data, because if what I have shown is not the molecule, 

 then no human eye has ever seen the molecule, and it is 

 my audacity in stating that nature will show tliis object if 

 we approach her with a neutral mind, which makes Mr. 

 Edser say that " nothing could well be more startling than 

 such a claim." The fact is, the deductions I have arrived 

 at are built up from many more experiments than time 

 permitted me to show Mr. Edser, especially experiments 

 interpreted by the thermopile and the thermometer. 



Frederick Hovenden. 



West Dulwich, July 9th, 1903. 



RARE CONDITION OF THE HUMAN HAIR. 



TO THE EDITORS OP KNOWLEDGE. 



Sirs, — Dr. Walter Kidd's note under this heading 

 is interesting, but I hai-dly think he is warranted 

 in concluding that the abnormal condition he describes 

 may have been inherited. 



It would be first necessary to ascertain that the part 

 where the truncated hairs appear had not been subjected 



