^12 



SGIENGE. 



[N. S. Vol. VII. No. 163. 



■distance from the sea and a sufficient altitude 

 are reached, another region of cloud is encoun- 

 tered, so that there are two cloudy zones, 

 separated by a zone over which the sky is pre- 

 vailingly clear. This contrast was well seen by 

 the writer at the beginning of the cloudy season 

 in December, on trips between Mollendo, on the 

 coast, and Arequipa, 80 miles inland in a direct 

 line, 7,550 feet above sea-level. The same three 

 zones were passed through on a trip up the 

 Oroya Railway, from Callao, at sea-level, to 

 Oroya, 12,178 feet above the sea. 



As to the cause of the coastal cloud, that 

 would seem to be found in the prevalence of 

 cool southerly and southwesterly winds — the 

 spiral outflow on the eastern side of the South 

 Pacific anticyclone — blowing along shore or 

 obliquely on shore along the whole desert strip 

 of the Pacific coast of South America. These 

 northward blowing and hence warming winds 

 flow from a cool ocean surface on to a warmer 

 land. They, therefore, becoming warmed, are 

 increasing their capacity for water vapor, and 

 instead of being rain-bearing, as might be ex- 

 pected in the case of on-shore winds which are 

 forced to ascend by the topographic conditions, 

 they are hostile to the production of rain. It 

 is true, to be sure, that the adiabatio cooling 

 due to their enforced ascent over the low coastal 

 hills is sufficient to produce cloudiness, but it 

 does not seem sufficient, in most cases, to pro- 

 duce precipitation. North of Paita, where the 

 cold ocean current and the southerly winds 

 turn off" to the westward, the barren strip comes 

 to a sudden end, and the coastal cloud, so 

 far as could be determined by the observa- 

 tions of only one voyage, comes to an end also. 



That the range of hills along the coast plays 

 an important part in the production of the 

 coastal cloud was shown by the fact that where 

 the immediate seacoast is low, as, e. g., at and 

 for a short distance north of Pisco, there the 

 coastal cloud was absent. 



R. Dec. Ward. 



Colon, Colombia, January 12, 1898. 



newcomb's philosophy of hypek-space. 



There is in Professor Newcomb's beautiful 

 address (Science, January 7, 1898) a marked 

 naivete. He says: "Certain fundamental 



axioms are derived from experience, not alone 

 individual experience, perhaps, but the expe- 

 rience of the race." On the contrary, the hered- 

 itary geometry, the Euclidean, is underivable 

 from real experience alone and cannot be even 

 proved by experience. Its adequacy as a sub- 

 jective form for experience has not yet been dis- 

 proved, but might in future be disproved. It 

 can never be proved. 



The realities which with the aid of our sub- 

 jective space form we understand under motion 

 and position, may, with the coming of more ac- 

 curate experience, refuse to flt in that form. 

 Our mathematical reason may decide that they 

 would be fltted better by a non-Euclidean space 

 form. But we are, and shall be, helpless to get 

 such a space form from any experience whatever. 



Space is presupposed in all human notions of 

 motion or position. We may drop out such 

 specifications from our space form as render it 

 specifically Euclidean, but we cannot replace 

 them by non-Euclidean. Euclidean space is a 

 creation of that part of mind which has worked 

 and works yet unconsciously. 



It is not the shape of the straight lines which 

 makes the angle-sum of a rectilineal triangle a 

 straight angle. With straight lines of pre- 

 cisely such shape, but in a non-Euclidean 

 space, this sum may be greater or less. In 

 non-Euclidean spaces, if one edge of a flat 

 ruler is a straight line the other edge is a curve, 

 if the ruler be everywhere equally broad. In 

 any sense in which it can be properly said that 

 we live in space, it is probable that we really 

 live in such a space. What becomes of the 

 dogma that fundamental axioms are derived 

 from experience alone ? 



George Bruce Halsted. 



Austin, Texas. 



SCIENTIFIC LITERATURE. 



Traits des variations du systeme musculaire de 

 Vhomme, et leur signification au point de 

 vue de I'anthropologie zoologique. Par Le 

 Dr. A.-F. Lb Double, Professeur de I'an- 

 atomie a I'Ecole de Medecine de Tours, avec 

 une preface de M. E.-J. Marey. En deux vol- 

 umes. Paris, Schleicher Freres. 1897. 

 During the last twenty years large numbers 



of scattered observations on muscular anoma- 



