December 7, 191 1] 



NATURE 



175 



LETTERS TO THE EDITOR. 

 [The Editor does not hold himself responsible for opinions 

 expressed by his correspondents. Neither can he undertake 

 to return, or to correspond with the writers of, rejected 

 manuscripts intended for this or any other part of Nature. 

 No notice is taken of anonymous communications.] 



The Weather of igii. 



With reference to Sir Edward Fry's letter in Nature of 

 November i6, the following figures may be of interest. 



We have some eighteen records of the temperature up 

 to a height of 15 kilometres or more over the British Isles 

 during the period of the hot weather, distributed over 

 seven days. Excluding the records for Scotland in Sep- 

 tember, where the weather was not hot, the following 

 departures from the mean are found : — 



At 2*5 kilometres a temperature of +5'5°C. 



5'o .. ,, ., +2-5° 



7 '5 •. .. ), normal 



100 ,, ., ,, normal 



12-5 „ „ ., -J-o" 



15-0 =, „ ,, -5-0" 



These figures show that the heat was confined to the 

 lower strata. With anticyclonic weather, such as pre- 

 vailed during the summer, it is usual to find a negative 

 departure from the mean temperature above 12 km. ; but 

 the greatest departure from the mean is generally found at 

 about 7-5 km., where, as a rule, we get +5° C. The 

 ;' -H5° C. at 2-5 and the normal value at 7-5 are very 

 unusual, but they are shown more or less in every record. 



I agree with Dr. Shaw in thinking that the surface con- 

 ditions are imposed upon us by the conditions that prevail 

 above. From the total and partial correlation coefficients 

 that I have obtained it seems to me that the pressure in 

 the layers of air just under the isothermal, which may be 

 takenas the pressure at 9 km., is the dominant factor in 

 ,the_ distribution of pressure and temperature in the whole 

 ' egion of the atmosphere that has been explored, with the 

 exception of the temperature near the ground, which in 

 temperate latitudes is certainly more dependent upon the 

 direction of the wind than upon anything else. 



I do not altogether agree with Dr. Shaw in thinking 

 that the changes of temperature at 9 km. are in any way 

 due to changes in the direction of the wind at that height. 

 It seems to me more likely that they are produced by 

 rising or falling air, and that the vertical motion, and 

 therefore the temperature, is the direct result of the varia- 

 tions of pressure. 



Unfortunately, it is only on rare occasions that we can 

 ascertain the rate and direction of the wind at great 

 heights ; but there is sufficient information to show us 

 whether the temperature at any given height up to 15 or 

 20 km. is dependent upon the direction and rate of drift 

 of the atmosphere as a whole, for the direction and distance 

 of the falling place of the balloon supply the requisite 

 information about the general drift on any particular 

 occasion. 



I hope shortly to tabulate the results of some 200 ascents, 

 and ascertain what the connection, if any, may be. 



Pyrton Hill, December 2. ' W. H. Dines. 



t: 



m 



The Interaction between Passing Ships. 



The statement made in Nature of November 30. in the 

 article on " The Interaction between Passing Ships," to the 

 effect that no experiments have been made to test this 

 interference in shallow water except those recently carried 

 out at Teddington, needs some little qualification. A 

 somewhat extensive set of experiments to test this, among 

 other points, was carried out some two months ago at 

 University College, Dundee. Screw-propelled models of 

 various sizes, at distances apart up to 200 yards, were used 

 in these experiments, the depth of water varying from 

 1-6 times the draught of the vessels to 12 times the 

 draught. The results were of such apparent interest that 



NO. 2197, VOL. 88] 



they were communicated to the Admiralty, who arranged 

 for the Teddington tests, of a more restricted nature, to be 

 carried out on larger accurate scale models of the Hawke 

 and Olympic. The results of the Dundee experiments have 

 been for some weeks in the hands of one of the scientific 

 societies, and it is hoped that they mav soon be made 

 public. A. H. Gibson. 



Engineering Department, University College, 

 Dundee, December 2. 



December Meteor-showers. 



The following meteor-showers become due during the 

 period December 8-31 : — 



Epoch December 7, i7h. (G.M.T.), second order of 

 magnitude. Principal maximum, December 8, 8h. 15m. ; 

 secondary maximum, December 8, 3h. 40m. 



Epoch December 7, 22h. 30m., approximately sixth order 

 of magnitude. Principal maximum, December 8, ih. 30m. ; 

 secondary maximum, December 9, ih. 40m. 



Epoch December 13, i7h. 30m., approximately sixth 

 order of magnitude. Principal maximum, Deceniber 12, 

 ih. ; secondary maxima, December 11, i5h. 30m., and 

 December 13, iih. 



Epoch December 13, i3h. 30m., thirteenth order of 

 magnitude. Principal maximum, December 14, 22h. 5m. ; 

 secondary maxima, December 13, 2ih. 5m., and December 

 16, i7h. 30m. 



Epoch December 18, 2h. 30m., thirty-fifth order of 

 magnitude. Principal maximum, December 18, igh. 50m. ; 

 secondary maximum, December 19, 7h. 40m. 



Epoch December 19, loh., approximately fifteenth order 

 of magnitude Principal maximum, December 19, 

 i3h. 50m. ; secondary maximum, December 19, i7h. 15m. 



Epoch December 22, ih., fourth order of magnitude. 

 Principal maximum, December 23, oh. 40m. ; secondary 

 maximum, December 22, 2ih. 30m. 



Epoch December 23, 2h. 30m., ninth order of magnitude. 

 Principal maximum, December 24, 6h. 30m. ; secondary 

 maximum, December 24, i8h. 15m. 



Epoch December 25, i5h. 30m., approximately twentieth 

 order of magnitude. Principal maximum, December 27, 

 i3h. 50m. ; secondary maximum, December 26, i5h. 



Epoch December 30, oh. 30m., approximately eighteenth 

 order of magnitude. Principal maximum, December 31, 

 i5h. ; secondary maxima, December 31, iih. 30m. and 

 i6h. 15m. 



There are reasons for believing that the total mass of a 

 meteoric maximum may be considerably greater than is 

 generally supposed. Such a mass of matter, in being 

 brought to rest, must give rise to currents in the upper 

 strata of the atmosphere, these currents very probably con- 

 stituting what may be known as atmospheric depressions, 

 inasmuch as a column of air if thus set in motion will 

 weigh less than when undisturbed. 



In December meteor-showers are more evenly distributed 

 over the month than was the case in November ; still, 

 there are periods of special meteoric activity. The first 

 of these, in intensity as well as in time, occurs on 

 December 8 ; the second period, as regards intensity, is 

 spread over the days December 22-24 ; while the third 

 period, which is comparatively weak, falls between 

 December 16 and 21. Shooting stars may be numerous on 

 the night of December 31. " John R. Henry. 



Dublin, December 4. 



The Inheritance of Mental Characters. 



To Dr. .Archdall Reid it is an " astounding thing " that 

 I should imagine that Prof. Pearson could possibly agree 

 with the interpretation I ventured to put upon his statement 

 which Dr. Reid condemns as " void of all content " and 

 " quite nonsensical." Dr. Reid evidently feels that my 

 quotation fro"m his attack upon Prof. Pearson was not quite 

 fair, in that I omitted part of the context which he regards 

 as essential. T apologise for an entirelv unintentional and 

 unforeseen cause of offence. As he has himself rectified this 

 omission, I may, I presume, take it that. all is en ividence 



