500 



NA TURE 



[September 23, 1S97 



over the whole of Turkestan, including Kasalinsk, Petrovsk, and 

 Alexandrovsk. At Tashkent, Samarkand, and Ura-tiube several 

 monuments of antiquity were damaged. A shock of earthquake, 

 accompanied by a rumbling sound and the falling of rocks from 

 the mountains, is also reported from the cantons of Grisons and 

 Glarus, Switzerland. — A very severe shock of earthquake was 

 experienced at Lima, Peru, on Monday, September 20. The 

 cornices of churches and houses fell, and the walls were 

 cracked. — At two o'clock on Tuesday afternoon, September 21, 

 two shocks of earthquake were felt at Rome and in other places 

 in Italy, including Rimini, Fermo, Recanati, Bologna, Sinigaglia, 

 Eabriano, Cagli, and Florence. The shocks were also felt at 

 Venice and Trieste. 



From an obituary notice in the British Medical Journal 

 -(September 18) we derive the following particulars of the scien- 

 tific career of the late Dr. A. F. Holmgren, whose death we 

 have already announced : — Holmgren was born at Asen, in 

 Linkopings Stift, on October 22, 1 831, so that at his death he 

 was almost 'sixty-six years of age. He studied at Upsala, and 

 then became a teacher of natural science in a school. He 

 graduated as M.D. in Upsala in 1861, and in the following year 

 was commissioned to spend some years abroad to study physi- 

 ology as it was taught by the great European masters. He 

 studied under Ludwig at Vienna, and under Briicke, du Bois 

 Reymond, and iHelmholtz ; while he also visited the schools of 

 Paris, London, and Italy. In 1864 he was elected professor of 

 physiology in Upsala, and built there the first physiological 

 institute in Sweden. His scientific work ranges over a wide 

 field, including his researches on the Negative Variation of the 

 Muscle Current (1862), a similar condition in the active heart 

 <l864) ; the action of poisons, calabar bean, chloroform, and 

 atropine ; the use of the ophthalmometer, and studies in colour 

 sensation. Perhaps his best-known works are those on Retinal 

 Currents. He showed the electrical currents of the retina, and 

 how they are influenced by light, not only white light, but also 

 the action of the various parts of the spectrum. He also showed 

 that the electrical variation caused by light depends upon the 

 retina only, and is not due to changes in the pigment, nor to the 

 action of light on other constituents of the eyeball. His atten- 

 tion was in the early seventies directed to colour blindness, and 

 in 1878 he published his well-known work on "Colour Blind- 

 ness in relation to Railways and the Navy," thus bringing to a 

 practical issue the work long before begun by George Wilson of 

 Edinburgh (1855). This led him to the invention of his now well- 

 known " worsted test" for colour vision. In 1889 he founded 

 and became the editor of the Skandanavisches Archiv fiir 

 .Physiologic, as he says in the preface, "not only to unite our 

 scattered forces under one flag," but to gain a powerful impulse 

 for the advancement of the science in the north of Europe. He 

 elected to publish all papers in German rather than Swedish for 

 obvious reasons. To the last, optical studies were his favourite 

 pursuit, and in 1891-92 we have a long paper in his Archiv " On 

 Elementary Colour Sensation." All who were present at the 

 Liege and Berne meetings of the Physiological Congress will 

 remember Holmgren's genial presence, his stately eloquence, 

 and his bonhomie. By universal consent he was perennial 

 President of the Congress, and few who saw him two years ago 

 would have thought that he would be so soon removed from his 

 sphere of activity. 



The expectations of the inventor of the Bazin roller-boat as 

 to the high rate of speed to be obtained with steamers without 

 increase of engine power, owing to the diminution in frictional 

 , resistance of the wheels or rollers on which it was proposed to 

 support the vessels, have not been realised. Accounts of this 

 boat appeared in Nature some months ago (vol. Iv. pp. 109, 

 379). Since then the machinery has been completed and trials 

 made on the Seine, which have shown that the action of the 

 NO. 1456, VOL. 56] 



j rollers does not decrease the frictional resistance of the water 

 I in the manner anticipated by the inventor, the adherence of the 

 [ water to the surface of the wheels as they revolve acting as a 

 j brake and checking the forward movement of the vessel. 



I A NEW process for producing artificial diamonds has been 

 experimented on successfully by Dr. Quirino Majorana 

 (liendtconti della R. Accademia dei Liitcei). The present 

 method consists fundamentally in heating a piece of carbon by 

 j the electric arc, and then submitting it to a violent pressure by 

 i means of a small plunger actuated by a piston, on which a 

 pressure of 5000 atmospheres was suddenly developed by ex- 

 plosion. When a sufficiently strong cylinder had been con- 

 j structed to withst.and this enormous pressure, the experiment 

 j produced a black mass consisting largely of graphite and 

 ! amorphous carbon. On employing Berthelot's method to isolate 

 the diamonds if they existed, small microscopic crystals were 

 obtained, mostly black and opaque, but which exhibited all the 

 properties of true diamonds, notably in their manner of burning 

 at a high temperature. The conclusion drawn from these 

 experiments is that pressure and heat are alone sufficient to 

 transform amorphous carbon into the crystalline or diamond 

 form, and that the presence of a metallic solvent, as in Moissan's 

 experiments, is not essential to the transformation. 



An optical device for the intensification of photographic 

 pictures is described by Lord Rayleigh in the Philosophical 

 Magazine for September. Photographers often obtain negatives 

 ! which are so thin that intensification by chemical processes is 

 insufficient to bring out any effective contrast between the 

 transparent and opaque parts. The method devised by Lord 

 Rayleigh is purely a physical one, and it may be described as a 

 j means of using a weak negative twice over. It is well known 

 that by placing a feeble transparency upon a sheet of white 

 j paper, the picture becomes clearly visible, even though nothing 

 j can be seen when the transparency is viewed by holding it up 

 i to the light. Through the transparent parts the paper is seen with 

 ! but little loss of brilliancy, while the opaque parts act, as it were, 

 j twice over, once before the light reaches the paper, and once 

 again after reflection on its way to che eye. This is the principle 

 of Lord Rayleigh's method. Instead of the paper, a flat 

 polished reflector is used, the film side of the negative being 

 , placed in close contact with it. On the other side of the nega- 

 I tive, and fairly close to it, is a condensing lens, which gives 

 parallelism to the rays from the candle used as a source of illum- 

 ination. The candle is placed just alongside of the copying lens ; 

 the light from it passes through the condensing lens, and falls as 

 a parallel beam upon the negative. After reflection, the light 

 again traverses the lens, and forms an image of the candle 

 centred upon the photographic copying lens. An optically 

 intensified positive is thus obtained, and by copying it in the 

 same way in the camera, a negative with more pronounced con- 

 trast than the original may be made. To obtain satisfactory 

 results, the false light reflected by the optical surfaces employed 

 I must be eliminated. In the case of the condensing lens the 

 j difficulty is overcome by giving the lens a slight slope with 

 I reference to the face of the negative. The false light reflected 

 from the glass face of the negative to be copied may be got rid 

 of by fixing a wedge-shaped glass plate to the glass side of 

 the negative by means of fluid turpentine. 



A DESCRIPTIVE list of mammals obtained from Somaliland 

 by the East African Expedition of the Field Columbian Museum 

 has been prepared by Mr. D. G. Elliot, and is now published in 

 the Zoological Series of the Museum's publications. The ex- 

 pedition was sent to Africa to procure for the Museum specimens 

 of the large wild animals which are rapidly becoming extinct. 

 It appears to have been " uncommonly successful in obtaining 

 ample series of nearly all the species inhabiting the country 



