1246 
magnetic field. For example, there is a phenomenon of 
“hydraulic induction” exactly corresponding to electro- 
magnetic induction, in which fluid currents develop in 
any closed circuit whose orientation changes in such a 
way as to change the flux of the earth’s rotation vector 
through the circuit.!° Ising was able to demonstrate 
this effect experimentally in an apparatus exactly cor- 
responding to a single-turn electric generator. 
One type of experiment suggested by the analogy 
would be to place a disc of fluid in a uniform magnetic 
field whose direction is perpendicular to the plane of 
the disc. The fluid would then be electrically charged 
and convection currents generated in it by appropriate 
heat sources or by other means. The Coriolis forces 
would be replaced by electromagnetic forces on the 
moving fluid, and the experiment would have the ad- 
vantage over rotating disc experiments of not involving 
a centrifugal force. A numerical check on this experi- 
ment was carried out by 8. L. Hess who found that 
the charges, electric potentials, and magnetic fields 
required to produce mechanically significant forces from 
such slow motions are so large as to make the experiment 
thoroughly impractical. Nevertheless, there are many 
other possibilities, and it is altogether likely that useful 
ones will eventually be developed. 
REFERENCES 
1. AHLBORN, Fr., ‘“‘Die drei grossen Zirkulationen der At- 
mosphare.”’ Beitr. Phys. frei. Atmos., 11:117-153 (1924). 
2. Airken, J., ‘‘On the Distribution of Temperature under 
the Ice in Frozen Lakes’’ (in Collected Scientific Papers, 
edited by C. G. Knort, pp. 30-33. Cambridge, Univer- 
sity Press, 1923) Proc. roy. Soc. Hdinb., 10:409-415 
(1879-80). 
3. —— “Notes on the Dynamics of Cyclones and Anticy- 
clones,’ Parts I and II, in Collected Scientific Papers, 
edited by C. G. Knort, pp. 488-458 (1900-01). Part III: 
ibid., pp. 459-467 (1915). Cambridge, University Press, 
1923. 
4, —— “Revolving Fluid in the Atmosphere.”’ Proc. roy. 
Soc., (A) 94:250-259 (1917-18). 
5. Anprigs, P., ‘‘Die Entstehung der Cyklonen.” Z. 6st. 
Ges. Meteor., 17:307-317 (1882). 
6. Brnorotsky, A., ‘‘Hinige Gedanken tiber die Bewegungen 
auf der Sonnenoberfliche.’’ Astr. Nachr., 114:153-154 
(1886). 
7. —— “Uber die Bewegungen auf der Sonnenoberflache.” 
Astr. Nachr., 124:17-22 (1890). 
8. Brzoup, W. von, ‘‘Experimentaluntersuchungen iiber ro- 
tirende Flissigkeiten.”’ Ann. Phys., Lpz., (8) 32:171-187 
(1887). 
9. Bserxnes, V., Die Kraftfelder. (Die Wissenschaft, Bd. 28.) 
Braunschweig, F. Vieweg & Sohn, 1909. 
10. —— “Uber thermodynamische Maschinen die unter Mit- 
wirkung der Schwerkraft arbeiten.’? Abh. sdchs. Ges. 
(Akad.) Wiss., Bd. 35, Nr. 1, 33 SS. (1916). 
1. Bovassn, H., Tourbillons, forces acoustiques, circulations 
diverses, Tome I. Paris, Delagrave, 1931. 
12. Czprmak, P., ‘‘Ueber warme Luft- und Flissigkeitsstr6- 
mungen.’”’ Ann. Phys., Lpz., (3) 50:329-334 (1893). 
10. In more usual meteorological terms, this is a simple 
consequence of the Bjerknes circulation theorem, and the 
experiment may be regarded as a demonstration of one aspect 
of the theorem, or, alternatively, of the rotation of the earth. 
LABORATORY INVESTIGATIONS 
13. DecHEVRENS, P. M., ‘Sur la reproduction expérimentale 
des trombes.”’ C. R. Acad. Sct., Paris, 105:1286-1289 
(1887). 
14. Deranm, A., ‘Theoretische Uberlegungen und experimen- 
telle Untersuchungen zum Aufbau hoher Zyklonen und 
Antizyklonen.”’ S. B. Akad. Wiss. Wien, Abt. IIa, 132: 
81-103 (1923). 
15. Dines, W. H., “Experiments Illustrating the Formation 
of the Tornado Cloud.” Quart. J. R. meteor. Soc., 22:71- 
73 (1896). 
16. Dover, H. W., ‘‘Hinige Bemerkungen tiber die meteorolo- 
gischen Aufsitze des Hrn. Vettin.” Ann. Phys., Lpz., 
(2) 102:607-613 (1857). 
17. Exner, F. M., ‘Uber die Bildung von Windhosen und 
Zyklonen.” S. B. Akad. Wiss. Wien, Abt. Ila, 132:1-16 
(1923). 
18. Ferre, H., ‘“‘Stromungsversuche im rotierenden Labora- 
torium.’’ Z. tech. Phys., 14:257-266 (1938). 
19. Fiscupr, K., ‘‘Untersuchung der Strémung in einer Zen- 
trifugalpumpe.”’ Mitt. hydraul. Inst. Miinchen, 4:7-27 
(1931). 
20. Frerman, J. C., Jr., ‘‘An Analogy between the Equatorial 
Easterlies and Supersonic Gas Flows.” J. Meteor., 5:138— 
146 (1948). 
21. FustwHara, S., “On the Growth and Decay of Vortical 
Systems.” Quart. J. R. meteor. Soc., 49:75-104 (1928). 
22. Funrz, D., ‘‘A Preliminary Report on Experiments with 
Thermally Produced Lateral Mixing in a Rotating Hemi- 
spherical Shell of Liquid.” J. Meteor., 6:17-33 (1949). 
23. —— ‘Experimental Studies of a Polar Vortex I.” Tellus, 
2:137-149 (1950). 
24. —— “Experimental Studies Related to Atmospheric Flow 
around Obstacles.”’ Geofys. pura e applicata, 17:89-93 
(1950). 
25. —— “Experiments Combining Convection and Rotation 
and Some of Their Possible Implications.’’ Proc. Mid- 
west Conf. Flu. Dynam. (May, 1950). 
26. —— and Long, R. R., ‘‘Two-Dimensional Flow around a 
Circular Barrier in a Rotating Spherical Shell.’”’ Tellus, 
(1951) (in press). 
27. GHataGcE, V. M., Modellversuche tiber die gegenseitige Be- 
wegung von Luftmassen verschiedenen Temperaturen. In- 
aug. Diss., Géttingen, 35 SS., 1936. 
28. Gopsxs, C. L., ‘‘Note on an Apparent Discrepancy be- 
tween Bjerknes-Sandstrém and H. Jeffreys.” Quart. 
J. R. meteor. Soc., 62:446-450 (1936). 
29. Gortumr, H., ‘‘Hinige Bemerkungen tiber Strémungen in 
rotierenden Fliissigkeiten.”” Z. angew. Math. Mech., 24: 
210-214 (1944). 
30. Haue, G. E., and Lucey, G. P., ‘Some Vortex Experi- 
ments Bearing on the Nature of Sunspots and Flocculi.”’ 
Proc. nat. Acad. Sct., Wash., 1:385-389 (1915). 
31. Harwoop, W. A., ‘‘Experiments on Frontal Waves.”’ 
Quart. J. R. meteor. Soc., 71:377-383 (1945). 
32. Haynes, B. C., ““A Density Channel for Illustrating 
Fronts and Occlusions.”’ Bull. Amer. meteor. Soc., 20:37- 
38 (1939). 
33. Hi~pEBRANDSsSON, H. H., ‘‘Wilcke’s Experiment zur Dars- 
tellung der Wettersiulen.”’ Z. dst. Ges. Meteor., 11:221- 
222 (1876). 
34. Istne, G., ““Die physikalische Méglichkeit eines tierischen 
Orientierungssinnes auf Basis der Erdrotation.” Ark. 
Mat. Astr. Fys., Vol. 832A, No. 18, pp. 1-23 (1945). 
35. JEFrreEys, H., ‘‘On Fluid Motions Produced by Differences 
of Temperature and Humidity.” Quart. J. R. meteor. 
Soc., 51:347-356 (1925). 
36. —— “The Function of Cyclones in the General Circula- 
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