Dec. ri, 1873J 



NA TURE 



103 



In No. 2 of the glass copies from the Ottumwa photographs, 

 1869, the moon is also apparently quite circular ; but in No. 4, 

 where the bright depths of the chromosphere are just appearing, 

 the polar diameter is distinct!)' the longest. I have been led to 

 conclude tliat the ellipticity is caused by an unequal eating over 

 or irradiation at the polar and equatorial portions of the limb, 

 and that in this lies proof that at the sun's equatorial regions the 

 brighter layers of the chromosphere extend to a greater height 

 than near the poles. We know from other sources that the corona 

 generally, and probably also its lower portions, were not so 

 bright in 1S70 as in 1S69 and 1S71 ; hence the eating over be- 

 tween the prominences lias been comparatively slight, and no 

 detectable difference has been caused between the polar and 

 equatorial diameters. A. CowPER Ranyard 



The British Museum 

 It is strange that such a statement as that advanced by Mr. 

 W. Stanley Jevons ill Nature, Nov. 13, has so long remained 

 unchallenged, viz. " that the British Museum exists not so much 

 for the momentary amusement of gaping crowds of country 

 people, who do not understand a single object on which they 

 gaze, as for the promotion of scientific discovery, and the ad- 

 vancement of literary and historical inquiry." No one will 

 dispute the truth of these statements, but substitute the word 

 *' instruction " for *' momentary amusement," and 1 very much 

 doubt if his views would meet with public approval. I have 

 always looked upon the British Museum as the Nation.al Museum, 

 and />-t'f/«/«<-«//)' the Museum of the people, and, as such, the ar- 

 rangement and labelling of "the specimens should be of the most 

 simple and insti'uctive nature : nor is such an object opposed to, 

 but perfectly coincident with, the highest interests of science. 

 No wonder the Museum is filled with "gaping crowds " when 

 nothing is done to instruct them as to the nature of objects of 

 which Mr. Stanley Jevons himself admits they are ignorant, nor 

 to provide them with a suitable and educational guide-book, 

 without which tliey are as sheep without a shepherd When the 

 Trustees of this Museum can spare time, they may, perhaps, be 

 able to direct attention to the fuller development of its scien- 

 tific and educational functions ; as regards the former, by the 

 establishment of one exclusively British Department ; and, as 

 regards the latter, by carrying out the very obvious suggestions 

 which I have advanced. The view that science, or rather scien- 

 tific men, should have a monopoly of the benefits to be de- 

 rived from this Institution is astoundingly selfisli and narrow- 

 minded. If such are the views of the Trustees, the British 

 Museum had better be closed to the public. S. G. P. 



Moraines 



I ir.WE recently been visiting some of those spots which, 

 according to Prof. Ramsay and other geologists, are marked by 

 moraines of the ancient glaciers of North Wales, and several of 

 which are supposed to form the retaining walls of lakes or tarns : 

 and a question has arisen in my mind to which neither my own 

 consideration nor any of the few books here at my command 

 has afforded any answer. 



A glacier which has retreated from its terminal moraine, 

 is always the source of a stream of water, and this stream 

 always cuts through the terminal moraine, and makes in it a 

 gap often wide, and always reaching down to the level of 

 ihe original soil. A terminal moraine from which a glacier has 

 retreated is the rim of a saucer with a cleft in it, extending to the 

 bottom of the saucer. It consequently cannot and does not act 

 as a retaining wall, and the water from the glacier does not form 

 a lake, but flows out as a stream. No better illustration of this 

 fact occurs to me than the Rhone giacier, with its long series of 

 terminal moraines, all intersected and cut through to the ground 

 by the infant Rhone. How then can a terminal moraine ever 

 lorm a lake ? But if a terminal moraine alone cannot form a 

 lake, a terminal moraine with a stopper put into its, hole might. 

 But how is the stopper to get there ? Why should d^bi is or 

 stones or any ether stopper stay in the one place in the whole 

 line where there is no resistance ? 



Where the basin of the lake is supposed to be constituted by 

 a rock basin and a moraine on its rim, what I have said has, of 

 course, no application to the rock basin, but seems to me to 

 apply to show that the moraine cannot constitute any part of the 

 retaining barrier. 



And again, where the retaining barrier is supposed to be con- 

 stituted by a marine terminal moraine, i.e. by a moraine depo- 

 sited under the sea, the observations I have made seem not to 

 apply. 



My questions apply to ordinary terrestrial terminal moraines. 

 They are so simple and go so to the root of the whole notion 

 that such moraines can form lakes that I presume they have been 

 answered long ago by geologists. Can any of your readers tell 

 me where such answers are given or what they oaght to be? 



Bryn Gwyii, Penmaenmawr, Oct. 13 Edw. Fry 



The Elevation of Mountains and the Internal Condi- 

 tion of the Earth 



I HAVE just read in Nature, vol. ix. p. 62, Captain 

 Hutton's letter to the Rev. Osmond Fisher on the " Elevation of 

 Mountains and Volcanic Theories." I was also indebted some 

 time since to the courtesy of Captain Hutton for a copy of his 

 lecture on the Formation of Mountains, delivered at Wellington, 

 New Zealand, November, 1872. Without entei'ing at present 

 into a discussion upon the ])articular theory which finds favour 

 with him, I may be permitted to call attention to the fact that 

 Sir William Thomson's views as to the rigidity of the earth 

 have been distinctly called in question in a former number of 

 this journal, which has probably not reached Captain Hutton. 

 I reier to my communication entided "The Rigidity of the 

 Earth," printed in Nature, vol. vii. p. 2SS. Captain Hutton 

 expresses his belief that the theory of internal rigidity has pro- 

 bably a weak point somewhere. I venture to think that its 

 weak points are so many as to make it a theory too brittle to 

 form a support to any geological superstructure. 



Dublin, November 28. H. Hennessy 



METEOROLOGIC SECTIONS OF THE 

 ATMOSPHERE 

 T^HE primary object of meteorology is to record the 

 ■^ pressure, the temperature, the moisture, the elec- 

 tricity, and the movements of the atmosphere. It is 

 desirable, however, that observations on these subjects 

 should be combined with the elements of time and 

 distance. At the general meeting of the Scottish Meteo- 

 rological Society on June 26, 1867, I proposed the method, 

 since generally adopted, of reducing the intensity of 

 storms to a uumerical value by the calculation of baro- 

 metric-gradients, or in other words by dividing the diffe- 

 rence of reading of any two barometers by the distances 

 between the stations where such barometers are placed, 

 thus introducing a nomenclature of universal application, 

 by which the movements of any aerial current, and par- 

 ticularly the wind force of storms, may in every part of 

 the world be reduced to one standard of comparison ; 

 and the calculation of thermometric, hygrometric, and 

 electric gradients was subsequently proposed. Since then 1 

 suggested to the same society the extension of this system 

 by the establishment of a series of barometers placed at 

 short distances from each other in one or more than one 

 direction in azimuth, so as to give horizontal atmo- 

 spheric sections for pressure. By means of such lines of 

 section the maximum gradient during storms might, from 

 the nearness of the stations to each other, be ascertained, 

 and thus the phenomena of local storms and other local 

 atmospheric disturbances investigated v/ith some hope of 

 success ; and since then a horizontal section extending 

 landwards from the sea-shore has been proposed for tem- 

 perature and moisture, chiefly with the view of determining 

 the extension inland of the influence of the sea on climate. 

 It would be important were the system of meteoro- 

 logical sections extended to the vertical as well as the 

 horizontal plane. If a string of stations were placed at 

 short horizontal distances from each other and extending 

 from the bottom to the top of a high hill or mountain, the 

 section thus obtained would show the relative distribu- 

 tion at different times, of pressure, temperature, humidity, 

 &c., in the vert cal plane. In Scotland, the existing 

 station of Drumlanrig is 191 feet, and that at Wanlock- 

 head 1,334 fe^t above the sea, so that the difference in 

 elevation is 1,143 ^fi^t- The horizontal distance between 

 them is 9 miles, and in all probability the necessary 

 number of intermediate stations could be established. 

 In Hong Kong the town of Victoria is 1,666 feet below 

 that of Blockhouse Victoria Peak, while in Switzerland 



