May 14, 1896J 



NA JURE 



serious work in the Antarctic, or to equip an adequate 

 British expedition to co-operate with them by conducting 

 simuhaneous observations on the other side of the un- 

 known area. An expedition a few years hence would be 

 much less serviceable, because the value of consecutive 

 work is at most additive, while that of simultaneous work 

 is as the square, or some higher power, of the numbers 

 engaged. . 



For the first time a south-polar map on a good scale is 

 now available, thanks to the enterprise of Herr von 

 Haardt of X'ienna, and his publisher Holzel. It is on a 

 polar projection, and the scale of i : looooooo, approxi- 

 mately 160 miles to one inch. A special feature is made 

 of ice-conditions and ocean currents, and the tracks of 

 all the important southern voyages are laid down. But 

 the most impressive feature is the vast central blank 

 wherein lie hitherto untouched gold-fields of scientific 

 d.ita. Hih;h Robert Mill. 



THE HEIGHT OF LUMINOUS CLOUDS. 



1\ the Asironomischcn Nachrichtcn (No. 3347), Dr. O. 

 Jesse gives a short condensed account of some of 

 the main results that have been obtained from a dis- 

 cussion of all the observations made during the years 

 1889-91. The full discussion, entitled " Die leuchtenden 

 Nachlwolken," will, however, soon appear in the Publica- 

 tions of the Konig. .Sternewarte in Berlin. 



Perhaps the most interesting part of this work is that 

 which is based, for the most part, on a series of photo- 

 graphs taken simultaneously at Steglitz, at the Urania 

 Observatory, at Nanen, and at Rathenow, which brings 

 out prominently the fact that the height of these clouds 

 since the beginning of the phenomenon in 1885 has re- 

 mained for the most part constant. The first table given 

 by Dr. Jesse shows to a remarkable degree this almost 

 constant value obtained for the mean height of the clouds, 

 the actual total mean value being 82'o8 kilometres 

 + o'oog. The apparent constancy in the value thus 

 obtained for the height of these luminous masses is even 

 more surprising when it is remembered that the observa- 

 tions were not made exactly simultaneously, a task by no 

 means easy, so that the fast movements of the clouds 

 were liable to influence the results to some marked 

 extent. 



.\n examination of the facts, howe\er, seems to indicate 

 that if the observations had been made strictly simul- 

 taneously, then the zone in which these nocturnal masses 

 move might be considered narrower than the observations 

 ha\e as yet indicated. 



.\s the observations used in this discussion were inade 

 for the most part after midnight, the computed value of 

 the height to which they extend can only be said to hold 

 for those clouds observed at this time. .As a matter of fact, 

 however, the few observations made before midnight 

 indicate also roughly the same elevation as above 

 obtained, but the paucity of the observations renders 

 impossible any degree of certainty being attached to the 

 result obtained. 



.Another part of the investigation related to the question 

 as to whether the apparent height cf the clouds had 

 always been the same as that deduced from the observa- 

 tions extending over the years 1 889-9 L To answer this, 

 an examination of all the observations since 1885 was 

 made to see whether the zenith distances for the same 

 depression of the sun below the horizon had always been 

 the same ; which would necessarily be the case if the dis- 

 tance of the clouds from the earth's surface be assumed 

 to be nearly always constant. 



The observations employed were tlmse made by Back- 

 house, of Sunderland, in Kissingcn, ^md by Dr. Jesse 

 himself in Steglitz. \ condensed form of the table given 

 by the latter is as follows : — 



NO. 1385. VOL. 54] 



Uepr< 



6 

 9 

 8 



S 

 7 



In the year 1889 the phenomenon of luminous clouds 

 occurred on July 2, and was, fortunately, unusually bright, 

 rendering it possible to make numerous accurate 

 measures ; these Dr. Jesse gives in the following table, 

 and compares the results with those given above. The 

 numbers are as follows : — 



The Difference of the Zenith Differences on July 2, 1SS9, 

 from those found in earlier 1 'ears. 



Depression of Zenith distance of the Variation in 



sun below highest point of the Difference, height for i° error 



horizon. clouds. in measured Z.D. 



1889, July 2. Kroin taljle. 



km. 



11-4 77-5 ... 78-6 ... +\-\ ... 6-4 



117 ... 79-1 ... 79'9 . . -I-0-8 ... 7'o 



I2'6 ... S27 ... 82-0 ... -07 ... 8-2 



129 ... 83-1 ... 827 ... -0-4 ... 87 



After allowing for the numerous sources of error which 

 might account for some part of the large differences in the 

 fourth column. Dr. Jesse adds that the magnitudes of 

 these are such as to lead him to assume another source of 

 explanation, namely, in the arrangement of the particles 

 composing the clouds themsehes. It is probable that 

 the clouds vary very considerably in thickness vertically, 

 which would also affect the diftcrences to some extent ; 

 thus with decreasing zenith distances a largely increased 

 impression on the measured zenith distance of the clouds 

 would result. 



Setting aside, however, the question of the origin of 

 these small differences, the important main result of the 

 investigations still remains intact, namely, that from the 

 years 1885-91 the luminous clouds have always had 

 nearly the same mean height, namely 82 kilometres, or 

 about 51 miles. W. J. S. L. 



THE BISHOP OF RIP ON ON HUXLEY AND 

 SCIENCE. 



AT a meeting convened by the Leeds Philosophica 

 and Literary Society, held a few days ago, a resolu- 

 tion was unanimously adopted appointing a Committee, 

 consisting of the Mayor, the members of the Council of 

 the Philosophical and Literary Society, and all others 

 who volunteered to join, for the purpose of raising sub- 

 scriptions in aid of the Huxley Memorial Fund. We 

 rejoice at the formation of the Leeds Committee, but 

 another cause of gladness is the address delivered by the 

 Bishop of Ripon in support of the object for which the 

 meeting was held. In no uncertain voice. Dr. Boyd 

 Carpenter declared himself a supporter of the principles 

 which guided Huxley's noble life, and proclaimed the 

 righteousness of scientific truth. It is not often that 

 dignitaries of the Church speak so boldly for science as 

 Dr. Carpenter did at the Leeds meeting ; and on this 

 account, and also because many of our readers will be 

 glad to see this public recognition of Huxley's integrity 

 of thought and purpose, we gladly print a report, though 

 an abridged one, of the address. 



It would not be sttrprising to discover there are many in this 

 meeting who would be prepared to jmint out one or two special 

 and specific objections or diftkultics they have felt in regard 

 to I'rof. Huxley's teaching. I think, however, you will agree 

 with me that if we demand complete harmony of opinion, that 

 stupid unanimity which betrays either ignorance or thought- 

 lessness, before we dare to speak in lionour of any one whose 



