6o 



NATURE 



[May 23, 1872 



LETTERS TO THE ED/TOR 



[ T/u- Editor Joes not hold himself responsible for opinions expressed 

 by his cc} respondents. No notice is taken of anonymous 

 communications. ] 



Error in Kumboldt's Cosmos 



The following letter, fro-n Major-General Sir Henry James, 

 is addressed to Mr. J. Camck Moore in reference to liis com- 

 munication wliicli appeared in our columnsunder date April 18. 



"I am much obliged to you for sending ma Nature, with 

 your letter in it respecting the manner in which Humboldt has 

 UFcd the term 'Centre of Grivity of the Land,' by which he so 

 far misled Heischd as to make him double the height of the 

 mean elevation of the several continents. It is obvious that 

 Humboldt determined the mean height of their surfaces, and not 

 the height of the centres of gravity of the continents. He de- 

 termintd the height ol A B, not of C G. The centres of gravity 

 are, therefore, at half the heigh's given by Humboldt. 



"I have the mean elevation of the surface of Forfarshire de- 

 termined by the same^'method explained by you, and by which 

 Humboldt determineJnhe mean elevation of the surfaces of the 

 continents ; it was S56 feet above the mean level of the sea. 

 The mean height of the surface of Europe (not of the centre of 

 gravity) is, according to Humboldt, 67 1 feet, and this is quite as 

 high as I should have expected it to be from the known height of 

 Forfarshire, containing so large an amountj of mountainous 

 country. The mean height of the surface of Europe cannot be 

 double this, or 1,042. The height of the water-shed between 

 the Baltic, Black, and Caspian seas is only 1,100 feet. 



" I think, iherefor-e, both from the method of investigation 

 and from the r-esults, that you have taken a correct view of the 

 subject, and that you have done science a great service in point- 

 ing out the err-or into which Humboldt has fallen, and by which 

 he misled Herschel to so great an extent. 



"John Carrick Moore, Esq." " IIexry James 



Southampton, April 22 



Fertilisation of Dictamnus 



An arrangement for the distribution of the pol'en of /i/<- 

 iamniis Fraxindla, which I noticed last June, may interest some 

 of the botanical r'eaders of Nature. The plants will .shortly be 

 in flower, so that any one who is curious about the matter can 

 see it for himself. 



To suck the nectar of these flowers, bees stand upon the fila- 

 ments, which are nearly horizontal ; as the anthers are matured 

 they are brought up in turn, generally two at a time, by the 

 curving filaments, into such a po:ition that they rub against the 

 tail of a bee standing on the filaments. As soon as each pair of 

 anthers is emptied they retire, and give place to another pair, 

 and when the last are emptied the style curves up, and brings 

 the stigma into the s.anie position. 



The difference in appearance between the empty and full 

 antheri is very striking in dry weather. 



Any one who knows the plants must have observed that 

 they are very a'tractive to bees, and that they produce seeds 

 in great abundance. Christopher J. Hayden 



Newspaper Science 



The general public cannot fail to acquire some very extra- 

 ordinary as well as en-oneoas r.otions about many subjects re- 

 lating to ihe progress and application of the different branches of 

 Natural Science, if we are to jud^e fi-om sundry scraps of in- 

 foimation, daily communicated or reproduced for their instruc- 

 tion, in the columns of even the most inlluential newspapers. 

 Amongst recent examples of this style style of information we 

 might refer to the following : — 



'Geo;^raphy. — Under the heading, "Oysters from South 

 America," we find in the limes of May 16, the announcement 

 that the steamer Kafl'niria had last Sunday ' arrived at Hull from 

 Norfolk, Virginia.having on board a cargo consisting of 500 or 

 600 tons of oysters, &c." 



Geology. — The following is reproduced from the Mechanics^ 



Magamnem the Times of May 16: -" Per saltiim. — Nantwich 

 in Cheshire has for some years past been gradually sinking, 

 owing to the withdrawal of the lime from the salt lakes, which 

 underlie the town," &c. 



Chemistry. — In the Times of May 9 it is stated that " accord- 

 ing to an analysis made by Prof. Zinno, the elements of the ashes 

 that were thrown out from Mount Vesuvius are chlorine of soda, 

 sulphate of lime, magnesia, allumen, iron, tilanio, and siltx. " 



Metallurgy. — The Engineer of April 12, in a paragraph on 

 early iron making at Merthyr Tydvil, in South Wales, must 

 rather astonish metallurgists by writing of " bon s supplying 

 sulphate of lime " in the process. 



.Irchitecture. — In a somewhat elaborate article on the new so- 

 called Selenitic mo.tar, which in reality takes its name from the 

 introduction of a little sulphate of lime, which when native forms 

 the mineral called selenite in its manufacture, we are informed 

 that " the name given to the improved mortar indicates to a cer- 

 tain extent the nature of the improvement ; that it is in the 

 direction of combining selenious acid with a base," &c. It would, 

 indeed, be good tidings to chemists to find that selenious acid 

 had become so cheap as to allow of its being used for such pur- 

 poses ; unfortunately, however, the last price lists inform us that 

 silcnium, from which it is made, still costs three shillings per 

 drachm. 



Although it has been said that it is not reasonable to expect 

 scientific information from newspapers devoted to general topics, 

 we still contend that we are entitled, wdien newspapers do make 

 such statements, to demand that they shiU at least be free from 

 such gross blunders as those contained in the examples here 

 cited, and to which many others might be added. 



London, May iS D. F. 



The University of Freiberg 



A letter signed " Undergraduate," in Nature of May 9, 

 confounds the bchool of Mines in Freiberg in Saxony with the 

 University of Freiburg in Baden. The writer and others who 

 wish to know where certain subjects are best taught in German 

 universities will find much information in Ascherson's 

 " Deutscher Univcrsitats-Kalender." This small book appears 

 twice a year, giving the number of students and the names of 

 lecturers and lectures offered each term in thirty-one universities 

 of tier-many, Switzerland, and the Baltic provinces of Russia. 



Berlin, May 16 A. Otpenheim 



Denudation of the Mendips 



I.\ reply to the question of " Inquirer " in last week's number 

 of N.viURE, asking for explanation of a passage in my Address 

 to the Geological Society, allow me to observe that geologists 

 judge of the amount of denudation which hills formed by anti- 

 clinal axes, such as the Mendips and Ardennes, may have suffered, 

 by prolonging across the range of hills the outcropping edges 

 of the strata thrown up on the flanks of the axis, keeping each 

 bed and each formation in its relative place. Thu^, takrng the 

 thickness of the Somerset Coal measures, including the Mill- 

 stone grit, to be on the north side of the Mendips about 9,000 

 feet, and of the Carboniferous limestone 1,500 feet; the 

 whole of these, together with some upper part of the 

 Old Red sandstone, forming together a mass of not less than 

 10,000 to 12,000 feet, have been removed from the area of the 

 Mendips, the central axis of which is formed by strata of Old 

 Red sandstone. In the case of the Ardennes, in addition to the 

 Carboniferous strata, Devonian and Silurian strata are thrown up 

 along the central axis at angles which prolonged form great 

 prches, or rather a series of arches, over the hills ; for here and 

 there the intermediate synclinal curves bring in portions of the 

 Coal Measures, which have thus been saved from denudation, 

 ^vhile they show how much has been removed in the intei mediate 

 areas. The whole of the Coal measures, which are there rather 

 thinner than in Somerset, the Lower Carboniferous series, which 

 is much thicker than in England, together with the Devonian 

 and part of the Silurian series, forming together a thickness 

 probably of not less than 15,000 to 20,000 feet, are there removed 

 from tlie central area. 



It is, however, almost impossible to coniey an exact no, ion of 

 these great physical phenomena without illustrative sections and 

 diagrams; anel for these allow me to refer "Inquirer" to some 

 papers in which such sections are given, and in which the subject, 

 a very complicateel one, is specially treated, viz., Professor 

 Ramsay "On the Denudation of South Wales and the adjacent 



