July io, 1890] 



NATURE 



261 



land Meteorological Society on April 15. The chief subject of 

 discussion was climatic changes, which were considered in two 

 divisions : («) Secular changes, introduced by Prof. W. M. 

 Davis. He stated that secular variations have undoubtedly 

 taken place, but we cannot give specific explanations of them. 

 {b) Supposed recent changes, introduced by Prof. W. Upton. 

 Several long series of observations were examined, and, while 

 slight indications of periodicity were found, there was no trace 

 of progressive change. — Trombes and tornadoes, by M. H. 

 Faye (concluded from the May number). — Method of determin- 

 ing the direction of the wind by observation of the undulations 

 at the margins of the disks of the heavenly bodies, especially 

 the sun and moon, viewed through a telescope, by Don V. 

 Ventosa, of the Madrid Observatory. The author states that 

 there are always two points on the limb diametrically opposite, 

 where the undulations travel tangentially to it and in the same 

 direction, while in intermediate regions the waves appear more 

 or less inclined to the limb. These motions indicate by their 

 directions those of the wind which produces them. 



SOCIETIES AND ACADEMIES. 

 London. 



Royal Society, June 19. — " On the Changes produced 

 in the Circulation and Respiration by Increase of the Intracranial 

 Pressure or Tension." By Walter Spencer, M.S., Assistant 

 Surgeon to Westminster Hospital, and Victor Horsley, B. S., 

 F.R.S. 



The authors have made for some time the effect of an increase 

 in intracranial pressure or tension the subject of an experi- 

 mental inquiry, so far as the increase affects the circulation and 

 respiration. 



They conclude that the increase in intracranial pressure in- 

 fluences the circulation and respiration through the diminution 

 in the physiological activity of the medulla which it causes. 



The authors first give an historical resttmS of the work of 

 previous observers. 



The following is a summary of the chief results obtained : — 



I. The Heart. — A considerable increase of the intracranial 

 tension was required to influence the heart ; it became slowed 

 and finally arrested. This happened more readily after respira- 

 tion had ceased, and required a higher pressure to produce it 

 when artificial respiration was employed, whilst division of both 

 vagi nerves abolished any slowing or arrest. The arrest, when 

 produced, continued permanently, unless the pressure was quickly 

 removed, or arlificial respiration employed, or the vagi divided. 

 But if the pressure was maintained whilst artificial respiration 

 enabled the heart to start again, then the cardio-inhibitory in- 

 fluence was gradually lost, so that the heart returned from being 

 very slow to its normal rate, or increased beyond the latter until 

 the rate became equal to that seen after division of the vagi. 

 When the vagi were divided at this stage the rate of the heart 

 did not alter. 



The Blood Pressure. — A primary rise, small in the dog, larger 

 in the monkey, was followed by a fall distinct from that produced 

 by the slowing of the heart, and not necessarily accompanying it. 

 When the heart started again the blood pressure rose, finally 

 reaching the level seen after division of the vagi, so that no 

 further rise took place when this was done. The power of pro- 

 ducing a fall of blood pressure was easily lost. After division of 

 the vagi the blood pressure was raised by increasing the intra- 

 cranial tension and by artificial respiration, so that it could be 

 maintained at a level between 300 and 400 mm. Hg for con- 

 siderable periods. 



Respiration. — This was likewise impaired and arrested. Its 

 arrest reacted upon the heart and the blood pressure upon it, so 

 that after the rise of blood pressure respiration occurred, even 

 although a much higher intracranial tension was maintained than 

 had been sufficient to arrest it when the blood pressure was lower. 



II. By the direct application of pressure in the upper part of 

 the 4th ventricle a slowing of the heart with a rise of blood 

 pressure was caused, whilst respiration continued, so rapid as 

 even to be nearly three times the rate of the heart in some cases. 

 Pressure below the calamus scriptorius arrested the respiration 

 without directly influencing the heart, whilst in the lower part of 

 the 4th ventricle respiration was impeded or arrested along with 

 a fall in blood pressure, and some slowing of the heart, followed 

 by arrest, after the respiration had ceased. 



NO. 1080, VOL. 42] 



"On the Alleged Slipping at the Boundary of a Liquid in 

 Motion." By W. C. Dampier Whetham, B.A., Coutts Trotter 

 Student of Trinity College, Cambridge. Communicated by 

 J. J. Thomson, M.A., F.R.S., Cavendish Professor of Experi- 

 mental Physics, Cambridge. 



The experiments of Helmholtz and Piotrowski on the oscilla- 

 tions of a metal sphere suspended bifilarly, and filled with various 

 liquids, gave finite values to the slipping coefficients. The theory 

 of the flow of liquids through capillary tubes, applied to these 

 results, show that such an effect would produce a marked change 

 in the time of flow of a given volume of liquid. Poiseuille 

 showed that for a glass tube there was no slip, and it follows 

 that the flow through a gilt tube of about a millimetre in 

 diameter should be twenty times as fast as through a glass one. 



The time of flow of a given quantity of water through a glass 

 tube was observed, and the interior of the tube was then sil- 

 vered. The time was alwayr. the same for the glass and for the 

 silver surface. The velocity of flow was varied within wide 

 limits, and pushed near the point at which the flow ceases to be 

 linear. 



Other experiments were made on drawn copper tube?, which 

 also agreed with Poiseuille's laws. Even when the inte- 

 rior surface was modified by cleaning with acids and alkalies, 

 polishing with emery powder, coating with oil, or amalgamating 

 with mercury, there was no change in the rate of flow. There 

 is certainly no slip with substances which are wetted by the 

 liquid. 



Some preliminary experiments of Piotrowski on an oscillating 

 glass flask, the interior of which was afterwards silvered, were 

 then repeated, and it was shown that, when more precautions 

 than Piotrowski took were used, the friction on the flask was 

 the same, whether the surface was glass or silver. 



Physical Society, June 20.— Prof. W. E. Ayrton, F.R.S. , 

 President, in the chair. — Prof. A. W. Worthington made a 

 communication on the stretching of liquids. The three known 

 methods by which this may be effected — viz. the barometer tube 

 method, the centrifugal method, and the method of cooling — 

 were described, and the precautions necessary in filling the tubes 

 and in freeing the liquids from air discussed. With non-volatile 

 liquids, such as sulphuric acid, the tubes are put in communica- 

 tion with a good pump, and before sealing, the liquid in the 

 tube is kept at a higher temperature than that in the communi- 

 cating vessel, in order that a stream of vapour may be passing 

 outwards and carry with it any air liberated from the glass 

 during the process of sealing. Before using tubes by the centri- 

 fugal method the author finds it advantageous to subject them to 

 considerable "jarring" at intervals. This usually breaks the 

 liquid column, and liberates a small bubble of air which may then 

 be floated out. By repeating this many times, the adhesion of the 

 liquid is greatly increased. With these precautions he had sub- 

 jected water to a tension of 7*9 and sulphuric acid to one of 12 

 atmospheres. The cooling method of Berthelot {Ann. de 

 Chemie, xxx., 1852) was then tried. In this method the liquid 

 nearly fills a strong closed glass tube at a particular temperature. 

 On slightly heating, it expands and fills the whole tube, any 

 residual air being dissolved. On cooling again, the liquid re- 

 mains extended, and still fills the tube until at last it lets go 

 with a violent " click," and the bubble of residual air and vapour 

 reappears. The tension of the liquids tested under these circum- 

 stances have usually been calculated from the relative change of 

 volume on the assumption that the coefficient of extensibility is 

 the same as that of compressibility. The author exhibited and 

 described an apparatus by which the tension and the extension 

 can be measured simultaneously. The tension is ascertained 

 from the enlargement of the ellipsoidal bulb of a thermometer 

 sealed into the containing vessel, and the extension calculated 

 from the volume of the bubble after the click. The tension 

 thermometer had been calibrated by internal pressure, and in 

 determining the extension, correction is made for the change of 

 volume of the apparatus. By this method he had subjected 

 alcohol to a tension of 1 7 atmospheres, and found that the co- 

 efficient of extensibility is much less than that of compressibility. 

 It is not clear what causes the liquid to let go of the glass, 

 but it is found that the bubble can be caused to reappear by 

 passing an electric current through a wire sealed in the capillary 

 tube. Sir Wm. Thomson remarked that Prof. Worthington's 

 paper was a curious commentary on the usual mathematical 

 definition of " a liquid " as a substance which offered no re- 

 sistance to being separated into parts. Speaking of freeing 

 liquids from air, he said the beneficial effect of jarring could 



