Investigations of Infra-red Spectra ...Carnegie Institution of Washington, 1908 |
Parole e frasi comuni
absorption bands appears arid Arizona atoms basin bolometer branches calcite canyon carbon Carnegie Publication Catalinas cells cent Cereus chlorenchyma chlorophyll band clay color complete radiator cortex Covillea deposits desert diameter disk dunes emission bands emission curve emission spectrum energy curve epidermis examined fasciated feet fluorite forms Fouquieria splendens galvanometer glass groups hard bast heat inches infra-red Laboratory layer leaves lower maxima maximum medullary rays meristem metals miles moon Mountains Nernst glower observed occur Opuntia oxide parenchyma Parkinsonia Parkinsonia microphylla Phys pith plants plate platinum portion present Prosopis quartz radiometer rainfall reflecting power reflection bands region ring River rosettes Rubens salts sand Santa Santa Catalina Mountains selective reflection sensitiveness shrubs silicates slopes soil species specimen spectra stem substances sulphate surface temperature thermopile thick tion tissue transmission transparent Tucson Tumamoc valley vanes vegetation wave-lengths woody xerophytic μ μ
Brani popolari
Pagina 48 - A paper read by invitation at the meeting of the Cordilleran Section of the Geological Society of America at Berkeley, California, January, 1902.
Pagina 98 - ... dwellings and towns with a considerable population at one or even two hundred miles from the nearest supply of water. Even such facilities are not necessary to the sustenance of a population in deserts of the most extreme type as illustrated by the Sahara which has a population of two and a half million people. So far as the vegetation is concerned the actual number of individuals is much less than on a similar area in a moist climate ; this in fact is one of the chief characteristics of a desert,...
Pagina 165 - We have now to- consider one of the most useful radiation meters yet devised, viz, the bolometer which is simply a Wheatstone bridge, two arms of which are made of very thin blackened metal strips of high electrical resistance and high temperature coefficient, one or both of which are exposed to radiation. When thus exposed, their temperature changes, thus unbalancing the bridge, and the resulting deflection of the galvanometer gives a measure of the energy absorbed. The maximum sensitiveness of...
Pagina 32 - At these places may be found within a compass of a hundred feet the most vivid contrasts of rank swamp vegetation and water-loving plants having broad leaves and delicate tissues with the toughened, spinose, and hairy, xerophytic forms of the desert. The presence of the moist area of the delta has but little effect upon the climate of contiguous arid regions, although a popular supposition to the contrary promises fairly to be immortal. The relative humidity here is often as low as seventeen per...
Pagina 28 - ... with salt, and separated from each other by small mound-shaped elevations of a white, sandy, or ashy earth, so imponderous that it has been driven by the action of the winds into these heaps, which are constantly changing their positions and their shapes. Our mules waded through these ashy...
Pagina 80 - MACDOUGAL (loc. cit., p. 82): It may be said, in conclusion, that the facts disclosed as to the actual temperatures in the soil, the diurnal and seasonal change therein, lead to the belief that the differences in temperature of the aerial and underground portions of plants cannot fail to be of very great importance in the physical and chemical processes upon which growth, cell-division, nutrition, and propagation depend. The determination of the effect of differences in temperature between the roots...
Pagina 104 - Ages, there was an expansion of the lake, which cannot have been due to diminished use of the rivers for irrigation, for the population of the Lop basin at that time was greater than now, though not equal to that of the flourishing Buddhist times, a thousand or more years earlier. Finally, during the last few hundred years there has been a decrease both in the size of the lake and in the population about it. If...
Pagina 86 - Echinocacti1s wislizeni which was 60 cm. high and 35 cm. in diameter, growing about 75 meters north of the laboratory, was carefully exposed and the course of its roots mapped (fig. 3). The roots, as the figure indicates, were branched very freely. There were three main roots which arose from the base of the plant not far from 10 cm. from the surface of the ground, and FIG.
Pagina 82 - ... a small pinyon tree with a fitful movement of the air at a temperature of 80° F. During the first few minutes of the observations in which equalization of the negative pressure was in progress, the time in which a unit (100 milligrams) of water was taken up was as follows: 40, 45, 42, 48, 47, 50, 50, 50, 50, 50, 50 seconds, or at the rate of 2 to 2.5 milligrams per second. Half an hour later, at ioh 30™...
Pagina 68 - . cut them off near the base and carry them away to their retreats. Hilaria mutica is a true desert grass which finds a place high up on the slopes, where it makes patches of color visible for miles. Cassia covesii opens its yellow flowers and forms its pods early, while Franseria deltoidea, a low shrub, has its bur-like fruits ready to be carried away by any moving thing that touches them early in April. The most striking color of this period, however, is that of the globose clusters of...