December S, 1893.] 



SCIENCE 



^i§ 



there is every reason for believing that the existing law 

 of distribution may differ vastly from the law of perma- 

 nent distribution required by the kinetic theory of gases. 



Average number of molecules of gas to every one whose speed is sufficient- 

 ly great to overcome the attraction of the coiresponding body: 



^f f-00 





=:st i 



Moon's surface 3.6 610.0 2.7x10^- 6.gxio^i 



Surface of Mars 3920. 5.0x10^'* i.oxio^^ j.8xio-|'_^^ 



Earth's surface 6.0x10" 3.3x10" 2.3Xio2=» 4.5x10"— 



Earth's atmosphere at a 



height of 80 miles 2.3x10" 7.6x10'" s.yxio^'-^ i.sxio'^"" 



Sun at same distance as 



Earth 2.7x10=" 6.6x10"'^ 2.oxio"-'» 1.7x10"''" 



TABLE 2. 

 Relative densities of oxygen and hydrogen in a permanent distribution 

 taking their densities at the Earth's surface as unity: 



J] 



KO 



WO 



Earth's surface i 



Earth's atmosphere at a 



height of 80 miles 3859 



Moon's surface 3.1x10 ~-'^ 



At Moon's distance from 



Earth 4.6x10 ~ -' 



At Earth's distance from 



Interstellar space 2.7x10 ^2^' 



Relative densities in a permanent distribution, taking the average densit 

 of distribution of the gas in interstellar space as unity: 



So 



At Infinity i.o 



At Earth's distance from 



Sun 7.9x10= 



At Moon's distance from 



Earth 1.7x10= 



At Moon's surface 1.2x10= 



At Earth's surface 3.7x10= 



3.9x11 

 9.4X1C 



ON THE LIFE ZONES OF THE ORGAN MOUN- 

 TAINS AND ADJACENT REGION IN SOUTH- 

 ERN NEW MEXICO, WITH NOTES ON THE 

 FAUNA OF THE RANGE.' 



BY C. H. TYLER TOWNSEND. 



Thk range known as the Organ Mountains, in south- 

 ern New Mexico, was determined by the U. S. Geodetic 

 Survey, if I mistake not, to rise to a height of 8,800 

 feet above sea-level. Ihis altitude has been carefully 

 veried b}^ observations taken by Professor C. T. Hag- 

 erty, of the Civil Engineering Department of the New 

 Mexico Agricultural College. The western base of 

 the range is about twelve miles to the eastward of Las 

 Cruces, in Doiia Ana County. The range runs nearly 

 north and south for a distance of about twenty miles. 

 It varies in width from about four to eight miles, the 

 north extremity as well as the south one being much 

 narrower. It is intersected a little south of the middle 



'Read before the New Mexico Society for the Advancen\ent of Science, at 

 Las Cruces, April 6, 1893. 



by a wide and detoured pass known as Soledad Caiion. 

 The San Augustine pass divides the range near its north 

 end. About two miles to the north of this pass begin, 

 by common consent, the San Andres Mountains, a lower 

 range which extends on to the northward for about fifty 

 miles. About three miles south of San Augustine pass 

 is a rather high and more difficult drop in the range, 

 known as Bayler pass. The highest peaks of the 

 Organs are north of the centre of the range, and their 

 upper portions are mostly bare and nearly inaccessible. 

 There is a ridge between the southernmost two peaks 

 and those peaks to the north of them. This ridge is 

 probably 8,000 feet or more in elevation, and its high- 

 est portion is the point to which the zones given below 

 have been traced. It dips about 200 feet at its north- 

 ern end. 



The altitude at the western base of the range is about 

 4,800 feet, or 1,000 feet higher than the site of Las 

 Cruces, situated twelve to fifteen miles west on the edge 

 of the Rio Grande Valley. Thus the above mentioned 

 ridge is, roughly speaking, about 4,000 feet above the 

 surrounding country, or abotit 3,000 feet above the base 

 of the range. 



The various points above mentioned will be better 

 understood by consulting the accompanying diagram of 

 the range. It is only a diagram, no attempt ' having 

 been made to secure accuracy of detail. 



It may be stated that, to the northeast of the range, 

 stretch away the plains of San Augustine; while to the 

 northwest is the vast waterless expanse known as the 

 Jornada del Muerto, or Journey of the Dead, where 

 seventy miles has to be covered betw^een springs. To 

 the eastward of the range is a vast level sandy plain 

 which extends some eighty miles to the Sacramento 

 Mountains, and plains stretch away likewise to the 

 southeast, and for a less distance to the south. For 

 some of the beauties of the Organ Mountains, I would 

 refer the reader to a paper by Mr. Charles H. Ames, in 

 Appalachia for I Sg 2. The point reached by Mr. Ames 

 was the lowest part of the ridge above referred to be- 

 tween the peaks, being the dip at its northern end. 



Beginning at the east bank of the Rio Grande River, 

 in the bottom of the valley, and going eastward until 

 the highest portion of this ridge between the peaks is 

 reached, the following zones, in the order given below, 

 are encountered. The actual ascent to this ridge, dur- 

 ing which most of the data of the higher zones were 

 carefully noted, was made on Nov. 12, 1892. We left 

 the house at Riley's ranch at 9.00 a. m., and reached 

 the highest part of the ridge at about 12.15 p. ^'-i thus 

 making fully 3,000 feet in three and one-quarter hours. 

 Starting back at 12.30 ?. .m., we reached the house again 

 at 2.55 p. M. It should be stated that there was much 

 snow in the dense brush through which we passed in the 

 higher portions of the range, and that on many occa- 

 sions we had to proceed in a reclining attitude over long 

 stretches of smooth rock at an angle of about 35'^. The 

 house at Riley's ranch is 4,900 feet altitude, and the 

 ridge, as above mentioned, about 8,000 feet. 



Tornilto or Cottonwood Zone. 

 About 3,500 to 3,800 feet. 



Characteristic plants. — Prosopis pubescens (tornillo), 

 Populus fremontii var. wislizeni (valley cottonwocd), 

 Salix spp. including S. longifolia (willows), Aster 

 spinosus (spring aster), Helianthus annuus (common 

 sunflower), Helianthus ciliaris (dwarf sunflower), Xan- 

 thium sp. (cocklebur), Rhus sp. (sumach), Sphceralcea 

 angustifolia, Solidago sp. (golden rod), Baccharis an- 

 gustifolia (at its climax), mistletoe, grasses, etc. 



