April II, 1872] 



NATURE 



"unlucky paper" should be openly exposed, than that I should 

 be "damned with faint praise." 

 Hull, Aprils C. Stanil.'vnu Wake 



The Aurora of February 4 



The Scottish Meteorological Society has just received the 

 schedules of its observers in Iceland and Faro for February last. 

 At Stykkisholm, on the norlh-we=t of Iceland, auroras were seen 

 on each of the nights of the 3rd, 4th, and 5lh, an i at Thorshavn 

 an aurora of a remarkably red colour w.as observe 1 in the S.E 

 and S. in the evening of the 4th. It was also observed at North 

 Uist, Shetland, of a very red colour, and over all the S. E. of the 

 sky ; at Monach, the most western island of the Hebrides, and 

 at nearly all the 1 50 stations which report to the Society, appear- 

 ing at some places as early as 5 I'.M., and coTtinuing visible at 

 others till half-past one on the morning of the 5th. Major 

 Stuart, the Society's observer at Janina, Greece, also reports an 

 aurora on the 4th from 6 30 PM. to midnight. 



On the evening of the 4th much thunder and lightning occurred 

 in Monach, South Uis", Skye, and others of the Western Isles, 

 and on the mainland of Scotland adjacent, even as far inland as 

 Corrimony, fifteen miles west of Loch Ness. 



The weather preceding and following this aurora was very re- 

 markable. At Stykkisholm, 22° 43' \V. long., the mean height 

 of the barometer from the 30th of January to the 5th of Feb- 

 ruary was only 28798 inches, and the wind N. E. through- 

 out, except on one of the days, when it was E. At this same 

 place a ttorm of wind, with snow showers, beyan at i a.m. of 

 the 30th of January, and continued without intermission for 102 

 hours, or till 7 a.m. of the 3rd, on which day and on the 4th the 

 weather was fine and seasonable and '.he u ind light. 



At Monach, 7°34' W. long., a storm of wind began at 6 A.M. 

 of January 30 and continued to blow from \V. S. W. , S.W., and 

 S. tdl 2.30 A.M. of February 5, having thus lasted about 140 

 hours. 



On the west of Scotland and the Western Isle=, a heavy storm of 

 wind from S. or S. W. was blowing during the evening of the 

 4th, the sky being generally clear, and the aurora, consequently, 

 well seen. But at some places the sky presented a strange lurid 

 appearance, as the aurora appeared through the opening clouds 

 as they drifted pa^t. Shortly after the disappearance of the 

 aurora, the wind modera'ed and fine weather followed. 



But in ihe east of Scotland the storm from the south, accom- 

 panied with drizzle and mist, did not break out till the morning 

 of the 5 h, or some time after the aurora had disappeared. It 

 was to have been expected that an aurora extending over so much 

 of the earth's surface would be preceded, accompanied, and 

 followed by very different weather in different regions ; and we 

 have seen it coming thirty-six hours after a protracted period of 

 stormy weather in Iceland, closing an equally protracted period 

 of stormy weather in West Hebrides, and preceding a storm of 

 wind and rain in the east of Scotland. 



. Alexander Buchan 



Scottish Meteorological Society, Edinburgh, April S 



Having seen an account of the aurora borealis which was 

 visible in England on the night of Februiry 4, I think that you 

 or some of your scientific friends might like to know that a very 

 brilliant display of aurora was visible here and in other parts of 

 the West Indies on the same night. 



On the night of February 4, I was going from Porto Rico to 

 Puerto Plata in, roughly speaking, lat. 19" N., long. 48° W. The 

 aurora was first seen at 8. 30 P.M., was most brilliant at 10 p.m., 

 and gradually died away by midnight ; the corresponding times 

 at Greenwich would have been I A.M., 2.30 a.m., and 4. 30 a.m., 

 February 5. 



I have several times seen auroras off the Western Islands, but 

 only remember havirg seen one several years ago in the West 

 Indies. 



Tliere were no pillars or points of light in this aurora, but a 

 bright flush in the northern sky, which surged up and died away 

 again every now and then, and was brightest about 10 p.m. 



Stephen Dix 



H.M.S. Mersey, St. Thomas, March 14 



The aurora of February 4 was visible at this point, but seems 

 to have been unobserved, except by a very fev^. My position 



was on the deck of a steamboat on the river going from this 

 point to one 23 miles miles higher up. The aurora was first 

 noticed by me at about 7 p.m., hanging over the woods to the 

 no-'th east, and was mistaken by the Caplairr for a large fire, a 

 common occurrence in our pine forests. Soon after, the glow, 

 which was a very deep red, extended to the zenith, shading til' 

 there, whilst a much fainter red light appeared in the north- 

 west. 



My last observation was made at 8.30 p.m., and the light was 

 then still very strong in the northeast. Being then upon a train, 

 and passing through an unbroken pine forest, I could not note 

 the time of disappearance of the display. I saw no streamers. 



There was no auroi'a whatever to Ihe s:iuth at any time visib'e 

 from at least sunset to 8.30 p.m. The facilities for observin"- 

 the sky in that direction were peculiarly favourable from the 

 position upon the river. F. G. Bro.mkerg 



Mobile, Alabama, U. S. A , March 23 



On the Colour of a Hydrogen Flame 



A correspondent to your list number has troubled himself 

 to propound an elaborate theory, to account for the blue tinge 

 which he states is always exhibited by the (lame of hydrogen. 

 There are also several text-books on chemistry which assert that 

 hydrogen burns with a characteristic faint blue flanie. It is easy 

 to prove, however, that the llame of pure hydrogen has no blue 

 tinge whatever. The blueness so frequently associated with the 

 flame of hydrogen is really due to the presence of sulphur, a, is 

 shown in a little paper I published in the i'ldlosopliical Alu'^'aziiic 

 for November 1865.* It is possible that the facts mentioned in 

 that paper may be turned to a practical end by some of your 

 readers, and therefore it may not be altogether useless if I put 

 down — for such disposal as you deem proper — one or two in- 

 teresting phenomena associated wi;h the combustion of hydrogen. 



Ttiere must I imagine be some people who write text-books 

 on experimental science without having verified any of the facts 

 Ihey state. Otherwise one cannot account for some obvious 

 errors which are propagated from one writer to another. The 

 blueness of a hydrogen flame is one such error, and ano'.her still 

 more glaring can be traced back through several high authori- 

 ties. The fact is stated that a rod of iron, or a sewing needle 

 remains suspended in the centreof a helix of wire through which 

 an electric current is passing. So long as the helix is animated 

 by the current the iron is said to behave like Mahomet's coffin 

 and hang in the air without the least contact with any solid body. 

 But this is not the case, however strong the current, or small the 

 iron, or however the helix may be disposed. 



More serious errors than these are to be met with in some of 

 the little books on science for school use, that are now cropping 

 up like mushrooms. Heads of schools cannot exercise too much 

 caution in the introduction of text-books on sc-ence, for they 

 know how a poor class book once in a school is a most difficult 

 thing to eject. It is therefore impossible to over-estimare the 

 value of books for boys written by men like Profs. Huxley, 

 Roscoe, and Balfour Stewart. An extraordinary impulse 10 

 scientific teaching has been given by the manuals of these and 

 other eminent authors, and of the gladne^s with which such 

 books are received by elder boys I, like others, can testify. 



And now, as a teacher, permit me. Sir, to tender to the same 

 authors not only my own gratitude, but the genuine and hearty 

 thanks of younger boys for their simply delightful Science 

 Primers. W. F. Barrett 



International College, Spring Grove, W. 



[We hope to give in our next number a summary of the ex- 

 periments to which our correspondent alludes. — Ed.] 



Barometric Depressions 

 I HAVE only just seen Mr. Murphy's criticism on my paper, 

 which appeared in your columns on the 21st ult. I mtended 

 that paper as a continuation of one which appeared last year. 

 The former aimed at showing that the ordinary variations of the 

 barometer could not be explained by aqueous vapour ; the latter 

 at proving that they were accounted for by the heating and cool- 

 ing of dry air. Into this question of air rersiis vapour the earth's 

 rotation did not enter, and I consequently took no account of it 



* A year or two ago I was surprised and amused to read this iirvestigation 

 repeated in the pages of the Cpruptcs Rcndus. I forget the name of the 

 French chemist who contributed it to the Academy, but he was doubtless 

 of anything I had written on the subject. 



