August 28, 1896.] 



SCIENCE. 



271 



just as much by omitting brevicauda in the in- 

 stance quoted as by inserting carolinensis ? 



Moreover the adoption of such a practice will 

 necessitate the rearrangement of most of our 

 existing trinomial nomenclature, and in such 

 cases as the Song Sparrows or Horned Larks 

 among our birds it will be no small matter to 

 decide which of the numerous subspecies shall 

 be relegated to ' sub-subspecies ' and in which 

 instances the species name shall be omitted. 



Furthermore, is not an author who uses quad- 

 rinomials, expressed or implied, placing himself 

 in the same category with Brisson and other post- 

 Linnean authors who were more or less poly- 

 nomial ? And when we ignore their works en- 

 tirely, what right have we to recognize more re- 

 cent writers who are not consistently binomial ? 



In conclusion it seems to me a matter of 

 serious regret, when the A. O. U. Code of 

 Nomenclature has practically become the 

 standard for American zoologists and botanists, 

 to see a member of the A. O. U. Committee on 

 Nomenclature breaking away from the Code and 

 proposing such innovations as the above. Is 

 not such individual action directly opposed to 

 the ultimate stability of our nomenclature ? 



Wither Stone. 



Academy of Natural Sciences, 



Philadelphia, August 3, 1896. 



IMPOSSIBLE volcanoes. 



To the Editor op Science : I wish to echo 

 the protest expressed by J. Paul Goode in a 

 recent issue of Science, against the illustrations 

 of impossible icebergs, with which our text- 

 books are filled, and ask that impossible vol- 

 canoes be put in the same category. 



The picture which has done service in geog- 

 raphies for many years as a representation of 

 Popocatapetl is about as severe a libel on a 

 respectable volcano as one could well imagine. 

 A tall cross, such as no traveller in Mexico ever 

 saw, and luxuriant palms such as never grow 

 at the altitude from which Popocatapetl can be 

 seen, make up a tropical foreground beyond 

 which a symmetrical, snow-capped cone with a 

 slope of from 40° to 50° rises to an impossible 

 height and extends to an impossible magnitude. 



All this is untrue, and it would seem, consid- 

 ering the nvimber of excellent photographs of 



the volcano extant, unnecessary. Besides, it 

 tends to perpetuate a common misconception 

 as to the slopes and heights of mountains which 

 it is time to correct. Many of the pictures of 

 mountains appear rather to record the feelings 

 of the artist after he has climbed to their sum- 

 mit than to represent their actual profile. 



It ought to be generally understood that the 

 average slope of a mountain of any kind can 

 rarely be more than 85° and is usually much 

 less. During a recent visit to Popocatapetl, I 

 measured its slope from several points of view, 

 and found it never more than 30°. In making 

 a sketch of the volcano, however, I found that 

 I labored under the optical delusion which leads 

 one to exaggerate the steepness of mountain 

 slopes, and which probably accounts for their 

 usual faulty representation. The slope as I 

 represented it on the paper, with what I thought 

 to be a fair degree of accuracy, proved on hold- 

 ing the paper between my eyes and the volcano 

 to be far too steep. It was only after several 

 trials that I could give it the requisite flatness. 



