454 



NATURE 



[March io, 1898 



Aconine strengthens the cardiac systole, and is opposed to 

 the dislocation of rhythm produced by aconitine, to which it 

 therefore acts in a large measure as an antagonist and antidote. 

 On motor-nerve termination it has a curare-like effect. 



All the alkaloids examined reduce body temperature, though 

 in varying degree. 



In conclusion it is pointed out that, whilst the toxicity of 

 aconitine mainly depends on the presence of the acetyl group, 

 the introduction of two additional acetyl groups into the aconitine 

 molecule does not materially alter the pharmacological action, 

 but merely reduces the toxicity of the parent alkaloid. The 

 removal of the acetyl group abolishes the stimulant action upon 

 the respiratory centre and pulmonary vagus. It also favours 

 reduced activity in motor, rather than in sensory nerve endings. 



The benzoyl group — present in benzaconine, absent in 

 aconine — causes a peculiar and distinct modification in the 

 heart's action, associated with a disturbance of sequence never 

 witnessed after aconine. The curare-like effect of aconine, and 

 the intermittent failure of the stimulated benzaconine muscle, 

 are also traceable to the modification in chemical constitution 

 arising from the absence or presence of the benzoyl group. 



Attention is drawn to the practical bearing of the fact that 

 benzaconine and aconine, pharmacological antagonists of aconi- 

 tine, occur with it in the root of Aconitinunt Napellus, from 

 which the medicinal preparations of the drug are made. 



February lo. — " Contributions to the Theory of Alternating 

 Currents." By W. G. Rhodes, M.Sc. (Vict.). 



This paper was divided into two parts. Part I. dealt with a 

 method of finding the steady values of alternating currents in 

 any circuits or systems of circuits, without having to perform 

 integrations of differential equations which may be somewhat 

 complicated. 



Part II. was devoted to the consideration of the effects of 

 higher harmonics in E.M.F.s and currents on the values of the 

 impedances and reactances of circuits. 



Among other results it was shown that periodic E.M.F.s and 

 corresponding currents can in all cases be represented by simple 

 sine curves having the same root mean square values, and suit- 

 able phase positions depending on the time constants of the 

 circuits and on the periodicities of the harmonics present. 



February 17. — "On Artificial Temporary Colour- Blindness, 

 with an Examination of the Colour-Sensations of 109 Persons. " 

 By George J. Burch, M.A. 



By exposing the eye to bright sunlight in the focus of a burn- 

 ing-glass behind a red screen, a condition of temporary red- 

 blindness is induced during which scarlet geraniums appear 

 black and roses blue. Green-blindness and also violet-blindness 

 may be produced by similar means. 



The author has systematically investigated the appearance of 

 the spectrum during the colour-blindness induced by exposure to 

 intense light from various parts of the spectrum, and finds that 

 the red from A to B, the green near E, the blue half-way be- 

 tween F and G, and the violet at and beyond H, produce well- 

 defined and characteristic results, indicating that each of these 

 colours corresponds to a definite colour-sensation. 



In each case all direct sensation of the colour used for 

 fatiguing the eye is lost, but the observer is conscious of a 

 positive after-effect of the same colour, by which the hue of all 

 other colours is modified. The temporary abolition of any one 

 colour-sensation is without effect on the intensity of the remain- 

 ing colour sensations. Any two, or any three, of the four colour 

 sensations, red, green, blue, and violet, can be simultaneously or 

 successively exhausted. The observed facts are, in the author's 

 opinion, more in accordance with the Young-Helmholtz theory 

 than with that of Hering, but they imply the existence of a 

 fourth colour-sensation, namely blue. 



Physical Society, Feb. 26.— Mr. Shelford Bid well in the 

 chair.— The meeting was held at Eton College. The President in- 

 formed the Society of the resignation of one of its Hon. Secre- 

 taries : Mr. T. H. Blakesley, M.A. In doing so, he referred 

 to the many important services rendered to the Society by Mr. 

 Blakesley, and he expressed the Society's deep and general 

 regret that Mr. Blakesley should now feel unable to continue 

 them. The Council elected Mr. W. Watson to the office 

 of Hon. Secretary.— Prof. T. C. Porter, in whose laboratory the 

 meeting was held, said it gave him very great pleasure to wel- 

 come the Physical Society. Eton had been most properly called 

 "the English home of ancient classical learning," For the 

 education of youth, classics had proved themselves of cardinal 



NO. 1480, VOL. 57] 



value. He believed that other Fellows of the Physical Society, 

 with himself, desired that this revered tradition of classics should 

 be maintained at Eton ; at the same time, they would agree 

 with him that there was no better supplement to classics than a 

 fair knowledge of the natural sciences. Prof Porter then gave a 

 lecture, illustrated by lantern photographs, on " Observations on 

 the Peak of Tenerife." He also described his method for 

 measuring the diameter of the earth. The method consists in 

 observing the shadow cast by the Peak upon the sea, and 

 measuring the time that elapses between the moment when the 

 apex of the shadow touches the sea-horizon, and the instant 

 when it is eclipsed by the shadow of night. Prof. Porter called 

 attention to a phenomenon hitherto unnoticed, i.e. that the 

 heated air ascending from the Peak casts a shadow, seen as a 

 faint prolongation of that of the Peak ; it rises obliquely from 

 its apex. A photograph was exhibited, taken on a quarter- 

 plate, in which is visible the curvature of the horizon as viewed 

 from the altitnde of the Peak. An interesting series of unique 

 photographs, illustrating the conformation of the Peak and the 

 phenomena of sUnrise and twilight in that latitude, was also 

 shown. In regard to twilight he noticed that the first approach 

 of night, as observed looking eastward, is marked by a dark 

 border of about five degrees width, followed by a sky somewhat 

 lighter. The lecturer discussed also a new theory of geyser 

 action. The theories of Bunsen and others fail to explain why 

 the geyser-throat appears almost completely full at the end of 

 an eruption. This immediate refilling is the more remarkable 

 when it is remembered that some geysers of the Yellowstone 

 region discharge a million and a half gallons at each eruption, 

 and that the eruptions may occur at five-minute intervals. More- 

 over, the theories generally accepted assume steeper tempera- 

 ture-gradients than those in a region like Yellowstone. Prof. 

 Porter suggests that the phenomena are better explained on the 

 assumption of an arrangement of strata such as exists in artesian- 

 well districts, the throat or shaft of the geyser being in the posi- 

 tion of a well communicating with a subterranean stream — the 

 " tube " of the geyser. From the disturbed nature of the region 

 the tube of the geyser follows a waved course ; the "shaft" 

 rises from the crest of the terminal wave ; the other cre^s may 

 be steam-traps. Since a basin-like formation is characteristic 

 of all geyser regions, it is fair to assume that the end of the 

 tube remote from the shaft has an outcrop in the hills that form 

 the sides of the basin. By means of this outcrop, water con- 

 tinually flows into the tube. When the tube does not sink 

 deeply enough to attain the temperature necessary for the 

 generation of steam, a quietly- flowing hot-spring is the result. 

 But if, at any point, the tube descends to underground tempera- 

 tures sufficiently great, steam is formed, and is trapped at the 

 highest point of a bend. Ultimately this steam checks the flow 

 of water, until the accumulated head of cool water from the 

 hills overcomes the resistance, condenses the steam, and re- 

 establishes liquid continuity. Urged by the pressure behind it, 

 the stream is impelled towards the geyser throat ; it forces the hot 

 water before it until equilibrium is once again restored in the tube. 

 Prof. Porter afterwards exhibited a method for viewing lantern 

 projections in stereoscopic relief. A slotted disc rotates in front 

 of two lanterns. These project two stereoscopic views in rapid 

 alternation upon a screen, in such a way that the two projections 

 are approximately superposed. In the rim of the disc, other 

 slots are cut, through which the observer looks. The arrange- 

 ment of slots is such that the right or left eye is only able to see 

 the screen at the moment when its own picture {i.e. the picture 

 from the right or left lantern) is on the screen. When the rotation 

 is sufficiently rapid, the views appear as one, without " flicker," 

 in stereoscopic relief, — The President proposed votes of thanks, 

 and the meeting was adjourned until March 11. 



Entomological Society, February 16.— Mr. G. H. Verrall, 

 Vice-President, in the chair. — Mr. G. C. Champion exhibited 

 specimens of Isodernms gayi. Spin. , from the Straits of Magellan, 

 and /. planus, Er,, from Tasmania, both found by Mr, J. J, 

 Walker. The genus, Isoderma, belonging to the Aradidae, 

 afforded an interesting case of geographical distribution, the 

 only known species occurring in Chili, Australia and Tasmania, 

 — Mr. C. O. Waterhouse referred to the similar distribution of 

 other species of insects, which went to support the theory of a 

 former connection between South America and Australia. — Mr. 

 Champion also showed an example of Bagotis lutosus, Gyll., 

 from Sweden. This insect had been on the British list since the 

 time of' Stephens, but possibly in error, as all the examples he 

 had seen in collections were wrongly so named, — Mr, Jacoby ex- 



