644' 



'NATURE 



rjULY 22, 1920 



not seem to me really practical unless the time 

 required for a medical- qualification is increased. 



The time-table of the later years of medical study 

 is already so overcrowded, there is such urgent 

 demand for more time for pathology, for instruction 

 and practice in the wards, for the study of special 

 medical subjects, and for some course of instruction 

 in psychology, that it is difficult to see how any 

 more lectures on pure science subjects can be squeezed 

 in. It seems to me that the special need of medical 

 education at the present time is a carefully thought out 

 scheme of post-graduate studies, in which the teachers 

 of chemistry, physics, and biology would take part, 

 in all the large medical schools of the country. 



Manchester. Sydney J. Hickson. 



The Mechanics of the Glacial Anticyclone Illustrated 

 by Experiment. 



In various publications , issued during the past 

 decade ' the present writer' has treated the peculiar 

 air circulation which obtains above a continental 

 glacier. A ' number of well-known writers, among 

 them Sir John Murray and Buchan, had early pointed 

 out that essentially anticyclonic conditions ' obtained 

 over the Antarctic region as a region, but without 

 reference to any connection with the continental 

 glacier; while the late Admiral Peary was the first to 

 note the dominance of centrifugal surface-currents 

 over the Greenland continental glacier,^ which im- 

 portant observation was the starting point of the 

 writer's studies. 



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 w^ould a film 

 of oil from a model of similar form. The centrifugal 

 nature of this 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 

 the American Philosophical Society it is stated 

 (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 centrifugallv, and 

 so develop at an ever-accelerating- rate a vortex of 

 exceptional strength." 



It is, of course, fully realised that a domed surface 

 is not the only one which theoretically might be con- 

 ceived to produce such an anticyclone, but it is the 

 only one of which we have examples in Nature 

 bringing about such results. Any sort of pyramid 

 would suffice; the essential thing is that the surface 



1 " The Ice Masses on and about the Antarctic Continent," Zeitsch. f. 

 Gletscherk., vol. v., iqio, pp. 107-20. " Characteristics of the Inland-ice of 

 the Arctic Regions," Proc. Am. Philos. Soc, vol. xlix., 1910, pp. qe-ioo. 

 " Characteristics of Existing Glaciers" (Marmillan, ipti), 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. 28^-86. "The Ferrel Doctrine of Polar 

 Calms and i's Disproof in Recent Observations," Proc. Second Pan-American 

 Scientific Congress, vol. ii. , Sec. II., Washington, 1917, pp. 179-89. 



^ Geographical Journal, vol. xi., 1898, pp. 233-34. 



NO. 2647, VOL. 105] 



should have its convexity upwards rather than down- 

 wards. Either over a concave surface or about a flat 

 one the refrigerating engine cannot operate. 



With the view of demonstrating the relation of the 

 air circulation above a continental glacier to the ice- 

 dome, I have prepared some simple devices for ex- 

 perimentation. In the first experiment water was 

 used as the fluid medium to represent air in an 

 apparatus (Fig. i) which consists of a glass tank 

 12 in. by 6 in. by 6 in., containing at the bottom a 

 copper vessel of semi-elliptical cross-section to repre- 

 sent a portion of the domed surface of the glacier. 

 This copper vessel may be filled from below and quite 

 independent of the tank itself. When used for the 

 experiment the tank itself is filled with distilled 

 water at room-temperature, rendered slightly alkaline 

 by addition of sodium hydroxide. Phenolphthalein is 

 then sprinkled over the surface of the water in the 

 tank. It soon develops a dark-red cloudiness which 

 remains near the surface. When ice-water is 

 introduced into the copper dome the adjacent layer 

 of water is cooled by contact and slides off to either 

 side, thus drawing down the coloured water from the 

 surface so as to simulate the vortex and the outflow 

 of a glacial anticyclone. If Victoria green is used to 



Fig. I. — A glacial anticyclone simulated in water currents (with use of 

 Victoria green as a colouring dye). 



replace phenolphthalein as a dye, its crystals must 

 be supported by a container having a bottom of fine- 

 meshed screen, but in this case ordinary tap-water 

 may be employed, since it is not necessary to render 

 the water alkaline. 



A similar experiment may be carried out using 

 air as the circulating medium and smoke as the 

 visible substance which betrays the currents. It is, 

 however, less suited to photographic representation 

 of the circulation, and the device only is therefore 

 represented in Fig. 2. The device consists of a glass 

 jar open at the top, such as is in common use for 

 goldfish; within this jar is a metal dome to repre- 

 sent the domed surface of the glacier. This dome 

 when filled with ice-water at once develops strong 

 anticyclonic circulation of the air in the jar, and the 

 circulation can be made visible if a burning cigarette 

 is supported on a platform near the top of the jar 

 and near its central axis. The jar is covered by a 

 metal plate, the central portion of which is separate 

 and attached to the funnel through which the ice- 

 water is admitted to the dome and on the stem of 

 which is the platform that supports the cigarette. 

 The funnel may almost equally well be dispensed with, 

 and the dome, already filled with ice-water, introduced 

 into the jar with the hand. 



