322 



NATURE 



\Fcb. 22, 1872 



very high temperature, and therefore converted the drops of 

 water into the spheroidal state. There they bounded and danced 

 androUed aljout iilte pith balls under an excited electrical receiver. 

 Their constant rotation and well-known rippling motion gave 

 them an opaque appearance which caused them to resemble 

 closely a fine fall of hail. In fact, those to whom I pointed out 

 the phenomenon likened their appearance to a fall of dusty snow 

 at the mouth of a furnace. The sight was very striking and in- 

 teresting. The workmen had taken these spheroids to be par- 

 ticles of scale and dust swaying about in the currents of air at 

 the mouth of the furnace. 



I have seen many times the experimental illustration of 

 " Leidenfrost's phenomenon" at the mouth of a furnace, but I 

 had never before seen its practical, though accidental, develop- 

 ment, and in the incident which I have narrated above the in- 

 terest chiefly attaches to the great anhthesis of the fact and its 

 .appearance — snow at the mouth of a fiery furnace. 



W. H. Preece 



The American Eclipse Expedition 



I DEEM it but proper and just that I should correct a mistake 

 that has just met my eye in Dr. Schellen's excellent work on 

 Spectrum Analysis. 



On page 332 of the 2nd German edition we find " Dieerstere 

 Expedition wahlte unter der Anfiihrung von Professor Morton 

 die Stationen im Staate Iowa. 



"(I) Burlington mit den Beobachtern Professor Mayer, Ken- 

 dall, Willard, Phillips, nnd Mahoney, denen sich der als ge- 

 wandter Spectroskopist bekannte Dr. C. A. Young, Professor am 

 Dartmouth College (Hanover), und Dr. B. A. Gould fiir diepho- 

 tographischeti AiifnaJnn^u InymigcstdUn.^' 



In the English translation, edited by Mr. Huggins, the above 

 reads, "The first expedition, under the guidance of Professor 

 Morton, selected stations in the State of Iowa as follows :— 



"(i) Burlington, where its observers were Professor Mayer, 

 and Messrs. Kendall, Willard, Phillips, and Mahoney, together 

 with Dr. C. A. Young, Professor of Dartmouth College (Han- 

 over), well known as an experienced spectroscopist, and Dr. B. 

 A. Gould, to whose charge the photographic department was 

 committed." 



Dr. Gould had no connection with the photographic expedi- 

 tion, but placed himself under Professor Coffin's general organi- 

 sation, so that he could have facilities for making observations 

 on the corona, and in searching for the suspected intermercurial 

 planet. 



The Burlington station of the Philadelphia eclipse expedition 

 was placed under the direction of Dr. Mayer, and the photo- 

 graphs pointing page 337 of Dr. Schellen's work are two of the 

 five plates secured by him during totality. 



Also the diagram on page 338 is from Dr. Mayer's report on 

 the eclipse (published (Jctober 1S69), an abstract of which, with 

 accompanying copies on glass of the original negatives, was 

 presented by M. Delaunay to the Institute of France. The 

 Kev. T. W. Webb laid them before the Royal Astronomical 

 Society, when the report and the photographs were discussed at 

 length at the meeting of November 12, 1S69. 



Henry Morton, President 



Stevens Institute of Technology, Hoboken, New Jersey 



Mr. Spencer and the Dissipation of Energy 



Will you permit me to inquire, for the instruction of the many 

 who are familiar with Mr. Herbet Spencer's " Doctrine of Evo- 

 lution," and especially in regard to " First Principles," sec. 58, 

 referred to by Mr. Spencer in his paper in your number lor 

 February i, if the theory of the "Dissipation of Energy" 

 does not upset a very considerable and significant portion of Mr. 

 Spencer's " First Principles"? William S.myth 



Maidstone, February 12 



THE AURORA OF FEBRUARY 4 

 (^ N Sunday, the 4th inst. , was witnessed one of the most magni- 

 ficent displays of aurora which have been seen in Europe with- 

 in the past twenty or thirty years. To most obsen'crs in this coun- 

 try it appeared equal in magnificence to the two fineaurors seen 

 on Oct. 24 and 25, 1870, and which were especially grand in 



England ; but foreign observers could only compare it with those 

 seen in 1S31 and 1S36. But if we take all the attendant pheno- 

 mena into consideration, it will appear that, whilst others may 

 have equalled this one in grandeur and beauty, there is not one 

 which can compare with it either as to the wide extent of countiy 

 over which it was visible, or as to the strangeness of many of the 

 phenomena by which it was accompanied. The numerous letters 

 which have appeared in these columns the last two weeks 

 show how universally it was noticed in England, Scotland, and 

 Ireland ; but in addition to these, the letters and telegrams which 

 have appeared in the daily and weekly papers — both English 

 and foreign — show that it excited attention over a still larger 

 area. It is difficult to trace the exact limits of this area ; but when 

 we mention Paris, Cologne, Berlin, Malta, Constantinople, Egypt, 

 and India, it will be seen what a large extent of country is em- 

 braced. So far we have seen no account of it as hiving been 

 visible in the extreme north of Europe, as in Iceland, Norway, 

 Sweden, St. Petersburg, &c., where most aurorcp boreales are so 

 well displayed ; but, on the contrary, many of the cities in which 

 it was noticed are those which are commonly supposed to be 

 too far south for such phenomena to be seen. The importance 

 of this point will appear later on. 



To take England first. Mr. AUnatt sends to the Tiiius a 

 long description of the appearance of the aurora as seen by 

 him at Frant, which shows that it was first noticed at 6 P.M. 

 in the S.W., and that by 7 o'clock it had reached the zenith. 

 It disappeared at 7.45, but reappeared for a short time at 

 10.50 in the N. ; but "at 7.30 P.M. the whole heavens were per- 

 vaded by this abnormal southern aurora, that had now expanded 

 universally and dipped its supplementary bands into the northern 

 horizon." He also writes: — "The earth's electricity was so 

 powerful, that the gold leaves of the electrometer remained 

 diverged for a considerable time ! " Other correspondents de- 

 scribe it as seen at Blackburn, in Lancashire, at 7, " embracing 

 the whole southern sky from N.E. round to W. ;" from Faver- 

 sham, in Kent, as visible between 9 and 10 o'clock ; " from 

 Cambridge as having its maximum intensity about 10 ; at Swin- 

 don as commencing at 10 minutes past 7 and lasting till 10 

 o'clock, " and giving as much light as a full moon, every object 

 being clearly visible." But many observers had noticed it at 

 times considerably earlier than those just mentioned : thus, 

 "J.S.Ii.," writing in Nature last week from Gloucester, 

 "observed it at 5.30, just in the twilight, but it was then con- 

 fused with the rays of the setting sun ; but as the darkness 

 deepened the aurora came out alone, and was then extremely 

 beautiful." But still earlier was it observed at Hartlepool, 

 whence a correspondent writes, at 5 o'clock : — " The whole 

 of the southern sky was tinged with a most beautiful 

 rose colour, which, as darkness set in, extended towards 

 the zenith, where it culminated in a brilliant corona." This 

 very early manifestation of the aurora partakes very much 

 of the nature of a "day aurora," the possibility of which has 

 been so much discussed in these columns (vidi- Nature, vols. iii. 

 and iv.) To us there does not appear much difficulty in believ- 

 ing that these grand meteorological phenomena, whatever their 

 cause may be, are independent of merely relative time, and that 

 the reason why they are mostly observed at night is because the 

 purely local circum stances are then most favourable to their ob- 

 servation. That an aurora should wait till night-iime before it 

 manifests itself hardly seems probable, whilst, on the other hand, 

 that the more brilliant light of the sun should prevent auroral 

 displays being seen in the day-time is not only probable but is 

 borne out by what we know of the light of the stars and planets. 

 No one believes that stars only shine at nighttime, why then 

 should there be a belief that auroral displays take place only at 

 night-time, especially when it is remembered that the experiences 

 of polar travellers in their sunless regions are distinctly against 

 it ? But this is a digression arising from the fact that in com- 

 parative daylight we have distinct and independent evidence of 

 this aurora having been observed. In addition to those already 



