Quercus (Erythrobalanus) radiata n. sp.

Twigs stout, densely yellowish-tomentose, remaining somewhat velvety for several seasons. Buds rounded, small (2–3 mm. in diameter), somewhat tomentose. Leaves large (9-13 cm. long and broad), deciduous, pandurate-orbicular, at most deltoid-pointed, cordate-auriculate, not hollowed between the radiate aristate ends of the veins, dull and glabrous except for the impressed veins above, detachably rusty-tomentose beneath with the denuded surface somewhat bullulate; petiole yellow-tomentose, 3 x 10-15 mm. Flowers unknown. Fruit annual, very small, in somewhat loosely yellowstellate spikes 60-80 mm. long, densely fruited above the middle; cup very small (7-8 mm.), hemispherical, with thin appressed blunt fulvous-tomentose scales; acorn elongated ovoid, 8 mm. long,

canescent.

Western Sierra Madre of Mexico (Rose, 2230, Aug. 13, 1897), from the top of the range near Santa Teresa, Tepic,-the type in the United States National Herbarium, for the privilege of studying which I am indebted to Dr. Rose, of that institution.

Quercus (Erythrobalanus) Conzattii n. sp.

Twigs stout, gray-tomentose even through the second year. Buds ovoid, rather small (3x5 mm. or more), somewhat hairy. Leaves large (8-10x9-12 cm.), deciduous, orbicular, very obtuse to short-acuminate, cordate, very slightly hollowed between the tips of the aristate veins, glossy, glabrous except for the impressed veins and convex above, densely grayish-woolly beneath; petiole graytomentose, 3 x 5-15 mm. Flowers unknown. Fruit annual, small, in woolly spikes 40-50 mm. long, densely fruited throughout; cup small (scarcely 10 mm.), hemispherical, with thin appressed blunt glabrate scales; acorn ovoid, scarcely 10 mm. long, canescent.

Southern Cordillera of Mexico, at 2,000 m. (Conzatti, 1900, June 29, 1907), from the Cuesta de Huauchillo, Nochixtlan, Oaxaca, -the type in the herbarium of the Field Museum at Chicago, for the privilege of studying which I am indebted to Dr. C. F. Millspaugh, of that institution.

EXPLANATION OF PLATES.

Illustrations, reduced one half, of the types of Quercus Urbani, Quercus radiata and Quercus Conzatti; from photographs by the author.

THE FIXED GLACIAL ANTICYCLONE COMPARED TO

THE MIGRATING ANTICYCLONE.

BY WILLIAM HERBERT HOBBS.

(Read April 24, 1920.)

66

The discussion upon the General Air Circulation over the Antarctic" contained in Dr. Simpson's final report upon the meteorological observations made in connection with Captain Scott's last expedition,1 is devoted especially to my theory of the glacial anticyclone and the opposite conception of the glacial cyclone as set forth by Meinardus, the meteorologist of the German South-Pole Expedition. Simpson's summing up of his conclusions is, however, a trifle difficult to evaluate, for he says:

"On considering the whole of Hobbs' paper one cannot help feeling that in spite of his failing to explain the origin of the precipitation and the mechanism of blizzards he has made out a very strong case for the existence of an anticyclone over all extensive masses of inland ice and over the Antarctic in particular. Therefore one would be inclined to agree with the generally accepted idea that there is an intense anticyclone concentric with the Pole and covering the whole of the Antarctic Continent.

"On the other hand, however, Meinardus in his discussion of the results of the Gauss Expedition attacks the theory of the Antarctic anticyclone with great vigour and one must admit with most convincing success. We will therefore now examine the problem from Meinardus' point of view."

decide whether Dr.

From these paragraphs one is unable to Simpson favors the one or the other theory. The following citations from his monograph will indicate that he has failed to grasp the fundamental physical fact which is the raison d'être of the anticyclone, namely, the domed surface of the continental glacier:

"Hobbs . . . contends that an anticyclone exists over every extensive snow-covered land and takes the Antarctic and Greenland as the two most

1 George C. Simpson, D.Sc., F.R.S., Meteorology, British Antarctic Expedition 1910-1913, Vol. 1, discussion (pp. 326, pls. 5) and Vol. 2, Weather Maps, Calcutta, 1919.

pronounced examples. To the anticyclones which owe their origin to a snow-covered land Hobbs has given the name 'glacial anticyclone' and he has worked out at considerable length the meteorological features of such anticyclones" (page 248).

"In my opinion . . . the descending air in the anticyclones is very poor in vapour." (Citation from Meinardus on page 249.)

"One must agree with Meinardus in this matter and there can be little doubt that Hobbs has left unsolved what we shall see in the next section is the greatest problem of the Antarctic anticyclone, namely, the origin of the precipitation within the anticyclone."

On page 250 of his report several statements are made by Dr. Simpson in summarizing my views (such, for example, as that the air moves inward along the surface to replace the surface outflow of air) which are without warrant and in common with the entire chapter reveal a very careless reading. I have therefore no recourse but to restate some of the more essential elements in my conception of the glacial anticyclone and to call attention to the several papers in which I have dealt with the subject. Among later ones I would note especially a paper in the Proceedings of this society.3 In all my writings upon the glacial anticyclone I have been at much pains to explain that the domed surface of the ice is essential to the development both of the anticyclone and of the alternating calms and blizzards which record its strophic action. In my "Characteristics of Existing Glaciers" it is stated (p. 149): “It is due to the peculiar shield-like form of this ice-mass that the heavier cooled bottom layer (of air) is able to slide off radially as would a film of oil from a model of similar form. The centrifugal nature of this

2" The Ice Masses on and about the Antarctic Continent," Zeitsch. f. Gletscherk, Vol. V., 1910, pp. 107-20. "Characteristics of the Inland-ice of the Arctic Regions," Proc. Am. Philos. Soc., Vol. XLIX., 1910, pp. 96-109. "Characteristics of Existing Glaciers" (Macmillan, 1911), Chaps. IX. and XVI. and Afterword. "The Pleistocene Glaciation of North America Viewed in the Light of our Knowledge of Existing Continental Glaciers," Bull. Am. Geogr. Soc., Vol. XLIII., 1911, pp. 641–59. “Earth Features and their Meaning" (Macmillan, 1912), pp. 283-86. The Ferrel Doctrine of Polar Calms and its Disproof in Recent Observations," Proc. Second PanAmerican Scientific Congress, Vol. II., Sec. II., Washington, 1917, pp. 17989. "The Mechanics of the Glacial Anticyclone Illustrated by Experiment," Nature, July 22, 1920.

3" The Role of the Glacial Anticyclone in the Air Circulation of the Globe," Proc. Am. Phil. Soc., Vol. 54, 1915, pp. 185–225.

motion tends to produce a vacuum above the central area of the ice-mass, and the air must be drawn down from the upper layers of the atmosphere in order to supply the void. It is here that is located the 'eye' of the anticyclone." Again (p. 266): "This anticyclonic circulation of the air is not determined in any sense by latitudes but is the consequence of air refrigeration through contact with the elevated snow-ice dome, thus causing air to slide off in all directions along the steepest gradients."

In my monograph published in the Proceedings of this society it is stated (Vol. 54, p. 188): "It is because the inland-ice masses have a domed surface that they permit the air which is cooled by contact to flow outward centrifugally, and so develop at an everaccelerating rate a vortex of exceptional strength."

Despite the statements of Meinardus that the descending air within the anticyclone would be very poor in vapor, a statement which is approved by Simpson, we now know from the records of several Polar expeditions that within the eye of the glacial anticyclone there is found an area of calm with shifting light, variable winds and excessively high humidity which results in mist or fog or even showers of ice needles, whereas all about are outwardly directed air currents associated with relative low humidity.

From the Antarctic glacier we have the record of Amundsen made in the vicinity of the southern pole and that of Captain Robert Scott, who entered the same region about a month later. From the Greenland glacier we have the scientific reports of two professiona! and highly experienced meteorologists, de Quervain and Wegener, that of the former from about the median line of the ice-dome near latitude 68° N., and that of the latter from near the very

center.

Captain Amundsen entered the central area of the Antarctic icedome near the 88th southern parallel, finding there what he believed to be a region of permanent calm or of light winds and of generally clear weather. The snow surface was smooth with no drifts. For

a fortnight the sky was clear except on two days when there were snow flurries. Insolation was so intense that perspiration poured from the bodies of the men even when most of their clothing had been removed.