February i6, 1905] 



NA TURE 



565 



repeated for three days without a hitch at from 200 to 

 300 fathoms, the flimsy net emerging from its trials on 

 every occasion with success. 



There are two practical points. The first is the art 

 of plunging the net at the surface, the ne.xt that of 

 whipping it out on reeling in, so that there may be no 

 contamination of surface organisms during the critical 

 moments. With a highly expert sounding crew such as 

 1 had at my service this was easily done. 



.My repeated experiments were also addressed to this 

 point, viz. to ascertain the best rate of descent and ascent 

 of the net, and mv experience was 100 fathoms a minute. 

 The flimsy net stood all tests. 



To the modern marine naturalist, whose complicated 

 (and expensive) opening and closing tow-net is an object 

 of worship, this* simple advice may seem like telling him 

 to " bathe seven times in Jordan "; he wishes to do a 

 great thing. George Murray. 



Februarv 5. 



The Sxth Sate'l te of Jupitfr. 



The author of the article on the sixth satellite of Jupiter 

 in N.-^TURE of January 19 has obviously made a slip in assum- 

 ing that the " retrograde " motion ascribed to the satel- 

 lite means retrograde in the sky, and not in the orbit. 

 .According to the ephemeris, Jupiter on January 4 was moving 

 direct, i.e. eiistivard, about 225" daily. The satellite was 

 west of the planet (position angle 269°), approaching Jupiter 

 at the rate of 45" a day, and, therefore, moving eastward 

 (direct) about 270" daily. 



The position angle on January 17, according to the latest 

 bulletin from Mount Hamilton, was 266°, having decreased 

 3° ; the distance of the satellite had decreased from 45' to 36'. 

 If the object is really a satellite this necessarily indicates a 

 retrograde orbital motion, unless the plane of its orbit is so 

 much inclined to that of the other satellite-orbits as to make 

 the new one pass north of the planet at inferior conjunction 

 instead of south as the others now do. 



The observations thus far published would, however, apply 

 equally well to an asteroid a little within or bevond the 

 orbit of Jupiter, and near perihelion in an orbit of .some 

 eccentricity and with a mean distance from the sun somewhat 

 greater than that of Jupiter. We must wait for further 

 observations to determine the truth. C. A. Young. 



Princeton, N.J., U.S.A., February 3. 



The Circulation of the Atmosphere. 



1 I1A\'E read \\*ith great interest vour review of Prof. 

 11. H. Hildebrandsson's report on " The General .Motion 

 of Clouds " (N.M'URE, t'ebruary 2, p. 329). 



.Ml his observations appear to support the theory of my 

 father, the late Prof. James Thomson, as set forth in the 

 Bakerlan lecture on " The Grand Currents of .Atmospheric 

 Circulation " (Phil. Trans., vol. clxxxiii. p. 653, 1892) and in 

 his earlier paper read before the British Association in 

 ■«.=i7- 



Is it possible that Prof. Hildebrandsson has not seen 

 these papers, and -has accepted theories put forward as 

 Prof. James Thomson's instead of referring to the 

 originals? Anyone who takes the trouble to read these 

 papers carefully must see that it is distinctly stated that 

 the main direction of the upper current of the atmosphere 

 is from west to east while moving steadily and gradually 

 towards the Poles, and that the air keeps this west to 

 east motion as it sinks to a lower level, and becomes the 

 great return current towards the equator. This motion 

 can hardly be termed " vertical circulation." As for 

 Prof. Hildebrandsson's assumption concerning Hadley's 

 theory, I should like to quote the following passage from 

 my father's paper ; — 



" In 1735 George Hadley submitted to the Royal Society 

 the paper of which I have made mention already as 

 supplying for the first time a substantially true theory 

 of the primarily dominant conditions of atmospheric 

 circulation. The paper is entitled ' Concerning the Cause 

 of the General Trade Winds,' and it is right here to notice 

 that Hadley applied the name ' General Trade Winds ' not 

 merely to those winds of equatorial regions to which the 

 name Trade Winds is ordinarily restricted, but uses it as 

 including also the west to east winds known to be pre- 

 valent in higher latitudes, and used in trade by mariners 



for ocean passages from west to east. Thus the scope 

 of his theory must be understood as being much wider 

 than what would be conveyed in ordinary nomenclature by 

 the name Theory of the Trade Winds." 



So far then from opposing Hadley's theory, my father's 

 amplifies and completes it. J.-VMES Thomson. 



22 Wentworth Place, N'ewcastle-on-Tyne, February 6. 



Remarkable Temperature Inversion and the Rtcent 



High Barometer. 

 During Friday and Saturday, January 27 and 28, the baro- 

 metric pressure over the south of England was exceptionally 

 high, readings of 31.00 inches being observed at 6 p.m. 

 on Saturday in the extreme south-west of the country. In 

 the neighbourhood of London the barometer rose to 3090 

 during the night of January 26, and remained at about 

 that height. until the morning of January 29, a well marked 

 anti-cyclone with readings over this value being shown on 



4-*'/" 



so'r 



-Tempe: 



t Oxiho 



, Sur 



the morning and evening weather charts of January 27 

 and 28. 



During such conditions it is in general impossible to raise 

 a kite, owing to the want or lightness of wind ; but on 

 January 28, during the afternoon, there was sufficient 

 breeze from the west to start a kite carrying recording 

 instruments, and to take them to a height of 3600 feet. 

 .A very remarkable temperature inversion was found to 

 exist, the details of which are shown in the accompanying 

 chart. .At 3.40 p.m. the surface temperature was 47°o F. ; 

 at 4.45 p.m. it had fallen to 45°-o F. The temperature 

 decreased steadily to 40° F. at 3000 feet ; a little higher 

 a rise of 12° took place, the temperature at 3300 feet being 

 52° F. At 4.28 p.m., at 3600 feet, the temperature was 

 53° F. Unfortunately, the humidity trace on the meteoro- 

 graph partially failed, but it suffices to show that the 

 temperature inversion was, as such inversions in my ex- 

 perience always are, accompanied by extreme dryness of 

 the air. 



The wind was west at the surface, and shifted gradually 

 to north-west at the highest point reached, but there was 

 no sudden change of direction at the height where the 

 temperature inversion occurred. 



I do not wish to imply that the high barometer and the 

 temperature inversion are necessarily correlated phenomena, 

 but the coincidence is interesting. W. H. Dines. 



Dates of Publication of Sciertiiic BookE. 



With reference to the complaint of IVIr. R. P. Paraiypye 

 (p. 320) that a big sum is still asked for Price's " Treatise 

 on Infinitesimal Calculus," I should be obliged if you 

 would allow me to point out that the price of this work 

 is, and has been for some time, 55. a volume. 



Henry Frowde. 

 Oxford University Press Warehouse, .Amen Corner, 

 London, E.C., February S. 



NO. 1842, VOL 71] 



