Nov. 28, 1889] 



NATURE 



95 



liotheque gencrale de rAstronomie," was presented by M. Faye, 

 who remaiked ihat this great con-.pilation would not be inter- 

 rupted by ihe death of M. Houzeau. The present volume 

 comprises biographies, didactic and general works, spherical 

 and theoretical astronomy, astronoujical tables for all epochs, 

 and treatises on calendars. 



Berlin. 



Physical Society, October 25. — The President, Prof. Kundt, 

 opened the meeting liy a warm expression of regret at the loss 

 sustained by the Society in the death of its late member. Dr. 

 Robert von llelmholtz. — Prof, von Bezold spoke on the various 

 causes which lead to the production of clouds and aqueous 

 precipitates. Using the graphic methods which he had himself 

 introduced into meteorology, he showed by means of diagrams 

 that the older ideas on this subject are insufficient, and that, 

 even in the case where both masses of air are saturated with 

 aqueous vapour, the precipitation which may occur when they 

 are mixed is not due to the mere mixing of warm and cold air : 

 the temperature of the mixture is not the mean of that of the 

 respective masses of air, but is somewhat higher, and the 

 amount of water which is condensed on their mixing is very 

 small. By means of his diagrams a simple solution is at once 

 obtained of many problems which have reference to the tem- 

 perature and humidity of masses of air when they are mixed 

 together in unequal quantities. It appeared that under the most 

 favourable conditions, when air .saturated with aqueous vapour 

 at 0° C. is mixed with air s^aturated at 20° C, under a pressure 

 ol 700 millimetres of mercury, only 06 grams of water is con- 

 densed out of 2 kilograms of the mixed portions of air. The 

 same mass of water would be condensed out of the same mass of 

 air saturated at 20° C. if its temperature were reduced to I9°'3 

 C, or if the air were to ascend through a height of 200 metres, 

 in which case its temperature would fall to 18° '9 C. Much 

 more massive aqueous precipitates are formed when moist 

 a'r is either cooled directly, or has its pressure reduced by rising 

 upwards, in which case a simultaneous cooling occurs. When 

 air saturated at 2d° C. is cooled down to io°7 C, — a tempera- 

 ture which results from mixing air at 24" C. with air at 0° C., — 

 44 grams of water are precipitated out of each kilogram of air, 

 and if the temperature is reduced to 0° C, 8 grams are preci- 

 pitated. Similar falls of temperature may be obtained during 

 an adiabatic rise in altitude. The conditions which hold good 

 for ■ super-saturated air may similarly be comprehended by this 

 graphic method. Notwithstanding that the formation of aqueous 

 precipitates by the mere mixing of two masses of air is thus 

 shown to be very minimal in amount, still it does occur in nature 

 as the result of this cause, as, for instance, in the case of cloud- 

 caps formed when different winds meet, and in the case of the 

 formation of ground-fogs. According to the speaker, clouds 

 ought to be distinguished by reference to the way in which the 

 precipitate of which they consist is formed, rather than by the 

 casual appearance which they present to the eye ; in any case, 

 mist and clouds must in the future be studied from the above 

 new point of view. — Prof, von Helmholiz added to the above 

 communication some remarks on the way in which the mixing 

 of two fluids of differeiit specific gravities is brought about, 

 iiuch mixing is only possible as the result of vortex move- 

 ments or of "breaking" waves. He had already dealt with 

 the production of vortices, and the production of waves has 

 recently engaged his attention, inasmuch as this problem has, up 

 to the present, only been regarded from a one-sided point of 

 view with reference to water, without taking into account the 

 influence of the air which is moving over its surface. When 

 wind blows over the surface of water, or when lighter air streams 

 over a mass of heavier air, waves are formed, whose size and rate 

 of propagation depend upon the relationship of the two fluids 

 which are moving one over tlie other. To obtain the mechanical 

 equations of these movements was the problem which he had 

 set before himself for solution in a communication which he had 

 recently made to the Berlin Academy. This dealt first with 

 waves on water, and then the conditions involved in these were 

 transferred to the consideration of waves in air. Waves i metre 

 long on the surface of water, which are frequently met with in 

 nature, correspond to waves in air 21 metres long — that is to 

 say, to air-waves which extend over a considerable stretch of 

 land. Waves in air are only visible in the ca-es where they are 

 accompanied by condensations of vapour, the latter occurring in 

 the case where the air rises several hundred metres to the crest 



of a wave. Prof. Helmholiz pointed out that the most important 

 outcome of the whole theoretical consideration of the problenv 

 was the following : a quiescent surface of water over which a 

 wind is blowing is in a slate of unstable equilibrium ; as the 

 result of this, waves are produced as soon as the wind acquires a 

 sufficient velocity, and the energy requirtd to raise the water 

 from the trough to the crest of each wave, as well as to produce 

 the onward motion of the wave, is derived from the more rapidly- 

 moving lower layers of air of which the w ind consists. Friction 

 plays a very subordinate part in the whole proce ss. 



November 8. — Prof, du Bois Reymond, President, in the 

 chair. — Dr. Pernet demonstrated the latest and newest form 

 of Edison's phonograph, and gave a minute description of 

 the apparatus, illustrating his remarks by means of two in- 

 struments which were exhibited to the Society. He prefaced 

 his description by a short historical introduction, from which it 

 appeared that several years before Edison's discovery, a French- 

 man named Gros had deposited with the Paris Academy a sealed 

 packet containing a statement of the essentials for the construc- 

 tion of a phonograph. 



Physiological Society, November i. — Prof, du Bois Rey- 

 mond, President, in the chair. — Dr. Rene du Bois Reymond 

 spoke on the striated muscles which occur in the small intestine 

 of the tench. The exceptional occurrence of striated muscles in 

 the small intestine of this fish has long been known, as also that 

 .when the intestine is stimulated electrically it contracts suddenh',. 

 as does a skeletal muscle. The whole intestine is surrounded by 

 these striated fibres arranged both longitudinally and circularly. 

 Further examination revealed a very thin layer of both longitu- 

 dinal and circular non-striated muscle-fibres, lying internally to 

 the striated fibres. The only other known case of a similar 

 occurrence of striated muscle-fibres in the walls of the small 

 intestine is found in Cobitis ; but in this fish the fibres do 

 not extend as far as the rectum, as they do in the tench. The 

 speaker set aside the idea that these striated muscle fibres are 

 connected with the respiratory function of the intestine, by show -^ 

 ing that other fish are also in the habit of swallowing air, and 

 that in such fish the mucous membrane of the small intestine is 

 extremely rich in blood-vessel.'--, whereas this is not the case in 

 the tench. He put forward the suggestion that the striated fibres 

 in the intestine of the ttnch are a transitional form between 

 unstriated and striated muscle-fibres, and based his views upon 

 the observation that, firstly, the reaction of these muscles is 

 alkaline, and, secondly, upon an analysis of an aqueous extract 

 of them. An aqueous extract of striated muscles contains, as is- 

 well known, three different proteids ; one which coagulates at 

 47° C, one which comes down at 56° C, and a thiid coagulating 

 at 70° C. The proteid which coagulates at 47° C. does not 

 occur in unstriated muscles, and was similarly found to be absent 

 in the extract of the striated muscles of the intestine of the 

 tench. The function of these last-named muscles has not as yet 

 been made out. — Prof. Fritsch spoke on the sensory organs in 

 the skin of fishes. Starting from the simplest forms in which 

 they occur as end-bulbs or tiny dilatations in the nerves whiib' 

 supply the several somites in the embryos of fishes, the Sj eaker 

 described their gradual change of form during growth. The 

 end-organ is always characterized by sensory cells — that is to say, 

 by cells whiih have a pear-like shape and are provided with a 

 sensory filament or hair, and are connected with nerve- 

 fibres. The developmental change which takes place is as 

 follows : at first the organ becomes protected by being set 

 deeper into the skin, spaces are then developed superficially to 

 the organ, and these are finally placed in communication with 

 the surface of the skin by means of a minute orifice or somewhat 

 lengthy canal. The lateral-line organs of fishes in several modified' 

 forms is developed as above described ; the sense-organ, with its 

 sensory cells and nerves, lying at its base. A furthtr modifica- 

 tion leads to the development of the closed vesicles of Savi, • 

 which are completely filied with a mucous secretion. In the 

 further modification of itiucture met with in the ampullae oF 

 Lorenzini, a change of functional activity is already marked, as- 

 shown by the fact that the sensory ctlls have lost their hairs and 

 have been converted into secretory cells. The speaker expressed 

 his concurrence with that view of the function of dermal sense- 

 organs, according to which they are to be regarded as auditory 

 organs in a low stage of evolution, set aside for the percepti< » 

 of vibrations and waves which are propagated through tlie 

 water. 



