142 



NA TURE 



[June i i, 1908 



must be known, and this information is furnished by llie 

 automatic recorder attached to the balloon. 



A comparison is made between the actual temperatures 

 and the adiabatic temperatures, i.e. the temperature which 

 a given volume of dry air would have if transported from 

 ground-level to a given height and allowed to expand 

 without receiving or losing heat. 



The height at which the pressure /> is found in these 

 circumstances is (if H = height of homogeneous atmosphere) 



// — H— ^ (l - m~ "^ j. (where in = plft-^, which gives 



a finite limit to the height of the atmosphere at 27 kilo 

 metres nearly. The ratio of the absolute temperatures at 



p and /)„ is Bi'e„(i!in) y ' 



For isothermal expansion dh = dy{pj p, and if the 

 arbitrary relation between temperature and pressure found 



F.R.S. The Lower Cretaceous formation of Bahia extends 

 along the coast to a point 130 miles south of the area 

 previously described. The fish remains are referable to 

 new species of the genera Mawsonia, Lepidotus, and 

 Scombroclupca. Mawsonia seems to have been scaleless, 

 and differs from all known Jurassic and Cretaceous 

 coelacanth fishes in lacking denticles on the fins. The 

 Lepidotus resembles the European Wcalden L. mantcUi 

 in proportions, but is more strongly ornamented. The 

 Scombroclupca is peculiar, in exhibiting only scales where 

 the anal finlets usually occur. — The Bala and Llandovery 

 rocks of Glyn Ceiriog (North Wales) : Dr. T. Groom 

 and P. Lake. The authors have mapped the district 

 around Glyn Ceiriog on the 6-inch scale. The succession 

 of strata is tabulated, and the characteristics of each bed 

 given. No indication of the overl.ap or overstep of the 

 Wenlock, Tarannon, and Llandovery beds mapped by the 

 ofificers of the Geological Survey or described by previous 



from the balloon records is 6ld^=^(p), the actual value of j observers \vas found, although there is probably an un- 

 conformity at the base of the Fron- * 

 Frys Slates. The beds of the district 

 dip northwards at an almost uniformly 

 low angle, but the structure is com- 

 plicated by a scries of faults, most of 

 which have hitherto escaped notice, 

 some being very elusive. The most 

 important east-and-west fault is the 

 Ddolhir fault, which dips at an angle 

 of 20° nearly with the bedc ng, and 

 may be either a thrust-plane s - a lag- 

 fau'lt. Of the N.N.W. and S'S.E. or 

 N. and S. faults, the most ren.arkable 

 is the Caemor fault, on the east side 

 of which the rocks have been raised 

 nearly a mile, and shifted horizontally 

 to the south for nearly three rniles. 



Faraday Society, Miy 26. — Sir T. 

 Swan in the chair. — Presidcniial 

 address : Some aspects of the work of 

 Lord Kelvin : Sir Oliver Lodge. The 

 president commenced by pointing out 

 the difficulty of doing justice in the 

 course of a short address to a man 

 who, from an early age to an old age, 

 had turned out such a prodigious 

 amount of work, embracing practically 

 all branches of physical science. Lord 

 Kelvin had calculated the age of the 

 earth, worked in the domain of electro- 

 statics, optics, elasticity, telegraphy, 

 beside many other practical subjecls. 

 These, however, had been dealt with 

 by other appreciators. Sir Oliver him- 



100 



200 



30O 



400 500 600 700 760 self would not touch upon the practical 



Pressure in m.m. of mercury. side of Lord Kelvin's work, but upon 



Diagram I.-Velocity of ascent of balloons. The ordinatcs give the taiio of the velociiy of a balloon *e more recondite and abstruse 



• . . ^ . , , ,, , Ai/A), ■ L 1 ■ branches of his artivitv. He was not 



m air at pressnre A canymg a load o-6 1.„,nndvv,th internal pressure =/+^-"^'-"bt.ng the efc.t.c prifj^ely able to agree' with some of 



compression and Fo the total lifting force at ground level), to the velocity at /o of the same balloon Lord Kelvin's assumptions, neither did 



if devoid of weight, and with the external and internal pressures tqual. For A, « = ioo ; for B, C, t „l,,,„„c rnnsirler thnt hia nrnrtinl 



and D respectively "=75, 50, and 30. i- 1 He always consioer tnat nis practical 



dh is dHtf>(l')[>„/p, the integral of which can readily be 

 found graphically. 



The relations of the height corresponding to a given 

 pressure on the supposition of (1) constant temperature, 

 (2) temperature as observed, (3) adiabatic temperature are 

 given, and it is noted that the observed decrement of 

 temperature is almost exactly 07 time the adiabatic decre- 

 ment down to a pressure of rather less than 200 mm., 

 corresponding to a height of 11 kilometres. 



Heights approaching 40 kilometres could probably be 

 reached if the balloons were made more expansible, i.e. if 

 the unfilled balloons were of thinner material and larger in 

 volume than those at present in use, as this would allow 

 of the same lifting force for the given quantity of gas and 

 give more scope for expansion with diminished pressure. 



Geological Soci-ty. M^v 20. — Plo^ \V. J. Snilas, F.R..''., 

 president, in the chair. — Some fossil fishes discovered by 

 Prof. Ennes de Souza in the Cretaceous formation at 

 Ilhtos, State of Bahia (Brazil) : .\. S. Woodward, 



XO. 2CI5, VOL. 78] 



always consider that his practii 

 w^orl< entirely bore out his con- 

 clusions. For instance, in the case 

 of the kinetic theory of solidity, Kelvin seemed to con- 

 sider that solids could be made from fluids and fluids 

 from solids, and that matter might be ether in motion. 

 But more recently he seemed to have rather changed his 

 views, or at any rate modified them, and seemed satisfied 

 with the postulate of action at a distance through space 

 without the intervention of a connecting medium. Sir 

 Oliver Lodge himself was unable to accept the explana- 

 tion of action at a distance without the intermediary of 

 some form of matter. Nothing in Lord Kelvin's work 

 was finer than his publications in 1851, or showed the 

 extraordinary keenness of mind aided by the tremendous 

 natural powers which he possessed. His prescience was, 

 at that date, even greater, than that of Helmholtz. 

 Posterity will probably consider that the greatest of all 

 his work was that upon the conservation of energy and 

 his enunciations upon the laws of thermodynamics. This 

 part of the discussion was illustrated on the blackboard 

 bv mathematical formula;. Reference was also made to 



