February 27, 1919] 



NATURE 



511 



interesting observations on the nesting habits ol tb 

 Kentish and little ringed plovers. The former spe< i< s, 

 he remarks, has a habit of embedding it- eggs in 

 the sand whenever thej have to be left unguarded, 

 no more than the broad end being exposed to view. 

 During incubation thej are brought to the surface 

 again, ["he actual hatching time tor the eggs o( the 

 little ringed plover that is to say, the time taken 

 from the "chipping" oi the shell to the complete 

 emergence of the chick- is not, apparently, less than 

 forty-eight hours. The downy nestlings of these two 

 speci< shed by their markings, 



yet, when the chick ol 



thai of ih. other, the parents do not seem to realise 

 that such .in exchange has be* n made. 



Proposals are on foot to develop and utilise the 

 -powei resources of Iceland. In an article on 

 the subject in La Gdographie (vol. xxxii., No. 3) 

 M. Rabot points oul thai the waterfalls of the island 

 could provide at least 4, ,ooo h.p. An Icelandic- 

 Norwegian company proposes to harness the Thorsa, 

 the longest river in Iceland, on which there are at 

 least six splendid falls available for industrial pur- 

 poses. Tin- Thorsa could provide Soo.ooo h.p. for live 

 months of the year, and not less than 1,100,000 h.p. 

 for the rest of the year; the largest fall could furnish 

 500,000 h.p. for seven months. It is proposed to use 

 this power in the manufacture of nitrates and sulphates 

 of ammonia. A further project is attracting the atten- 

 tion of the Danish East Asiatie Co. It proposes to 

 carry wheat from Port Nelson, on Hudson Bav, to 

 Iceland, and there to utilise the power of the Thorsa 

 River in milling it preparatory to export to Europe. 

 Despite the abundance of water-power, Iceland pre- 

 sents certain disadvantages in its development as an 

 industrial country. The frequency of earthquakes, 

 not to mention eruptions of lava, may interfere with 

 mechanical installations, illacial floods, which are 

 fnquent and violent, may also cause difficulties. 

 Lastly, the labour question will have to be solved, for 

 Iceland has not sufficient labour to meet the demands 

 of industrial development. 



Meteoroi.oc.h il O 11- Nos. 31 and 32, to 



February 1, issued monthly, show that a climatological 

 station has been established at Keswick, and observa- 

 tions will be used for the Monthly Weather Report 

 from January. A climatological station has also been 

 . stablished al Mrathpcffer, Ross-shire, so that, after 

 a break of about eighteen months, this northern spa 

 is again represented in the Monthly Weather Report. 

 There is the gratifying information of a Rainfall 

 Vssociation for Munster. Much need for additional rain 

 information for Ireland has been felt, especially with 

 the prospect of forestry and water-power. There is 

 promise of "the analysis of wind records at South- 

 port"; this discussion by Mr. J. Baxendell uses 

 twenty years' observations. Advance copies of a 

 " Manual of Meteorology," part iv\, are available for 

 official use. It gives "The Relation of the Wind to 

 the Distribution of Barometric Pressure," by Sir 

 Napier Shaw. It is stated that " it represents the 

 progress made chiefly by those who have been asso- 

 ciated in the work of the Meteorological Office in the 

 past twenty years." Circular No. 32 contains a scale 

 of surface visibility as adopted b) the Meteorological 

 Office, the Admiralty Meteorological Service, Meteoro- 

 1! Service Royal Vii Force, and the French Army 

 \|. t. orological Service. The scale <> t (( S is given in 

 metres and in miles ;it which objects are not visible 

 in good daylight, o not beyond 200 metres, and 8 not 

 beyond 30,000 metres or 18-6 miles. 



In the Revue gin&rale des Sciences for January 15, 

 Prof. F. M. Jaeger, of the University <>f Groningen, 



NO. 2574, VOL. I02] 



gives a risumi of the results which have been ob- 

 t'ii I in his laboratory during the last five years on 

 tin chemico-physical properties of substances at high 

 "|| eratures, The surface tensions of organic 

 liquids have been determined up to about 200 C, and 

 of fused sails up lo limn C, by the submerged 

 method. While the surface tensions of organic 

 diminish rapidl) with increase of temperature, 

 thosi ol fused salts change very little. The electrical 

 conductivities of the fused talts have also been deter- 

 mined up to 1600 C. in some cases. All the salts 

 investigated have conductivities which increase with 

 temperature according to a linear law. 



A -fries of articles has appeared dealing with the 

 radiation-characteristics of the incandescent mantle, 

 being chiefly an extension of the work of Rubens 

 on the thoria-ceria mixtures lo a large family of such 

 combinations. It exhibils the Welsbach mantle 

 (Journal of the Franklin Institute, November. [918) 

 simply as one of a group of possible combinations of 

 radiating materials. Tin- closest study has been 

 made of the behaviour under various conditions of 

 the absorption bands to which the enhanced visible 

 radiation of the more efficient mantles is due. No 

 explanation has been found for the occurrence of the 

 visible absorption bands of ceria and other materials, 

 but the information obtained as to the conditions 

 under which they appear and disappear has made 

 possible a fairly complete explanation of the different 

 behaviour of the mantle in flame and cathode-discharge 

 heating. 



In two papers published in the Proceedings of the 

 Tokyo Mathematico-Physical Society (ser. 2, vol. ix., 

 October, 1918) Mr. Keiichi Aichi makes an interesting 

 contribution to the hydrodynamical theory of density 

 or temperature seiches. By developing Love and 

 Rayleigh's treatment of oscillations in a fluid of 

 variable density, he arrives at an expression for the 

 period of internal seiches in a basin of uniform depth 

 with vertical sides, in which two layers of uniform, 

 but different, density are separated by a transition 

 layer in which the density varies exponentially. Lakes 

 of rectangular or circular shape alone are considered. 

 The interest of such a discussion is mathematical 

 rather than physical, as the theory takes no account 

 of shelving shores or irregularity of shape. There- 

 fore, for comparison of observed with computed periods 

 it is as satisfactory to assume the simple case of a 

 sharp discontinuity of density with uniform density 

 above and below the boundary. Chrvstal's treatment 

 of the problem, as developed by Dr. E. M. Wedder- 

 burn, though less rigid mathematically, affords a safer 

 method of comparison, as all the peculiarities of the 

 shape of the lake basin are taken into account, and 

 it is unnecessary to assume any arbitrary law for 

 the variation of density. Taking the case of Loch 

 Earn in August, 191 1 and 1913, temperature seiches 

 with periods of 152 hours and 195 hours respectively 

 were observed. The corresponding periods computed 

 by Dr. Wedderburn were 15-0 and 196 hours. Mr. 

 Aii hi, using the same data and employing his method 

 of calculation, obtains periods of 17 and 16 hours. 

 The papers conclude with some remarks on the pos- 

 sibility of internal seiches in the ocean, and it is 

 shown that in a tropical sea, 3 km. deep and 1000 km. 

 long, internal seiches with periods of from 3 to 4 days 

 m.iv be expected. 



An illustrated article in Engineering for January 31 



particulars of the double-reduction geared tur- 



iiin. s made by the Parsons Marine Steam Turbine Co., 



Wallsend-on-Tyne, for single-screw standard vessels. 



I is niv bi-di-pressure and one low-pressure tur- 



