1876.] 0-7 [Trowbridge. 



transcribing the language ; groupings of consonants rarely occur, in T. 

 frequently. One simple consonant generally heads the word and syllable ; 

 names for colors begin with a- or os-. The parts of the human frame 

 mostly terminate in -to, -co, -no, -son ; others begin with oko-, okun-,vf\nc\i 

 would not be altogether disparate from the T. akon man, provided it has 

 the same signification. It is true that the Caddo: nishe moon, ajkoto cold, 

 icinter bear some external analogy with tlie T. na-ashod moon and atsoj 

 cool, but there is often a wide difference between resemblance and real 

 affinity. I have given elsewhere a collection of T. words resembling to 

 terms of the surrounding idioms, which might be augmented indefinitely. 

 Only one of the compared languages has yielded a few terms resting 

 probably on real identity, and that is Aztec. "We find T. (ya-) x^ to eat, 

 ka (-la) mouth and Aztec (tla-) ka, ka (-matl); T. hauei, auvei great, large, 

 Azt. vei, huei ; T. &x water and Azt. atl. If these coincidences, which 

 Tonkawa has in common with many Sonora languages, are increased 

 by others, we may look out for proofs of old connections between the 

 two ethnical bodies; connections through commerce, expeditions, emi- 

 grations or immigrations, not as yet through ethnological affinity. Up to 

 this day a kinship of the Tonkawas with any other American nation or 

 tribe has not been shown, and neither Aztecs, nor Shoshones or Caddoes 

 can claim it on linguistic grounds. A faint resemblance could be traced in 

 two Caddo terms only and phonology as well as grammar disagrees in most 

 particulars from that of the Tonkawas. 



Note. — Remember well, that the x used here has nothing to do with the 

 English X, but represents the harsh, guttural aspirate kh unknown to the 

 English language. 



On the Atmospheres of the Sun and Planets. 



By David Trowbridge, A. M. 

 Bead before the American Philosophical Society, November 3, 1876. 



There are two cases to be considered ; in the first place we may suppose 

 the body surrounded with an atmosphere, to be so hot as to influence, to a 

 considerable extent, the density of the circumambient fluid ; and in the 

 second place we may regard the planet as cold like the earth, and as we 

 suppose, Mercury, Venus, and Mars. I shall suppose the atmospheres 

 composed of gases which are subject to the same laws as terrestrial gases. 



1. Let us suppose the solar or planetary body to be a sphere of radius r. 

 Also let z be the hight of any stratum of the atmosphere above the surface 

 of the planet ; p the density of that stratum ; Z the force of gravity at the 

 hight z ; g the force of gravity at the surface of the planet ; A the density 

 of the atmosphere at the surface of the planet ; p the pressure at the hight 

 z ; P at the surface ; t,, the temperature above 32° Fah. at the surface, and 

 t at the hight z ; X the coefficient of expansion ; or the fraction expressing 



