P OP TJLAR MIS CELL ANY. 



7i5 



may be the capacity of the race for develop- 

 ment in a state of peace, it is apparent, 

 from the great check on their increase be- 

 tween 1860 and 1S70, by the operations of 

 the civil war, that any serious disturbance 

 of their industrial pursuits, like a prolonged 

 foreign war or political convulsions at home, 

 would produce such distress as to disturb 

 profoundly their vital movements. The 

 same event would follow an over-produc- 

 tion of the staples grown by their labor, 

 owing to their habitual improvidence. Thus 

 far they have experienced no serious rivalry, 

 and therefore no check to their natural in- 

 crease. . . . This fact is undoubtedly fa- 

 vorable to the numerical increase of the 

 race, though it is equally clear that it tends 

 at the same time to delay its intellectual 

 improvement by deterring individuals from 

 pursuing other and higher industries. In 

 any event, there is little danger that either 

 race will severely encroach on the ground of 

 the other in our time, and no danger that 

 the colored population of any part of the 

 country will be in the way of the whites, 

 unless they should so far advance intellect- 

 ually and morally as to win a commanding 

 position by sheer force of merit." 



Northern Transcontinental Snrvey. A 



"Northern Transcontinental Survey" has 

 been organized in the interest of the North- 

 ern Pacific Railroad and its allied lines, 

 under the direction of Mr. Raphael Pum- 

 pelly, the purpose of which is to obtain a 

 satisfactory knowledge of the extensive, 

 hardly explored regions which may be made 

 tributary to those lines and their resources. 

 It has been divided into departments of 

 mineral resources, climate, rivers and irri- 

 gation, soils, forests, economic botany, labo- 

 ratory, and topography, which have several- 

 ly been put in charge of specialists. A 

 considerable amount of preliminary work 

 was done last year, the most important, 

 perhaps, of which related to the examina- 

 tion of the black coals of the western part 

 of the region under survey and of the brown 

 coal-fields of Dakota. The former coals 

 were found to be good steam-generators, the 

 latter not, except in combination or after 

 special preparation. Particular attention is 

 paid to the forest resources of the country, 

 in which we are glad to see that the eco- 



nomical use of the timber is not wholly left 

 out of sight ; and observations are making 

 on the useful grasses of the country. The 

 results of the surveys are to be cartographi- 

 cally represented, in a series of maps de- 

 lineating severally topographical, hydro- 

 graphic, climatic, and botanical features. 



Langley's Observations on Solar Radia- 

 tion. The scientific expedition of Professor 

 S. P. Langley, of the Alleghany Observa- 

 tory, to the summit of Mount Whitney, in 

 1881, has led to some important and novel 

 conclusions with reference to the effect of 

 the atmosphere on the action of the sun's 

 rays, and to the temperature of space. 

 Among the principal objects of the expedi- 

 tion were, to determine how much heat the 

 sun sends to the earth (the solar constant), 

 and what part of the surface temperature 

 of the planet is due to the sun's direct 

 radiant heat, and what part to the effect of 

 the earth's atmosphere in storing this heat. 

 Mount Whitney, in Southern California, was 

 chosen, because of the conveniences afforded 

 by its great height and the dryness of its 

 atmosphere, and because two stations could 

 be found upon it within easy signaling dis- 

 tance, and yet having a difference of more 

 than eleven thousand feet in elevation. One 

 of the earlier observations of the expedi- 

 tion was to notice, as former observers had 

 done, "that as we ascended, and the air 

 grew colder, the sun grew hotter, till our 

 faces and hands, browned as they already 

 were by weeks of sunshine below, were 

 burned anew, and far more in the cold than 

 in the desert heat. As we still slowly as- 

 cended, and the surface temperature of the 

 soil fell to the freezing-point, the solar 

 radiation became intenser, and many of the 

 party presented an appearance as of severe 

 burns from an actual fire, while near the 

 summit the temperature in a copper vessel, 

 over which were laid two sheets of plain 

 window-glass, rose above the boiling-point, 

 and it was certain that we could boil water 

 by the direct solar rays in such a vessel 

 among the snow-fields." This observation 

 induced the conclusion that if the earth's 

 atmosphere were withdrawn, the tempera- 

 ture of the surface would greatly fall, though 

 under a materially greater radiant heat ; and 

 Professor Langley expresses the opinion that 



