May 1, 1896.] 



KNOWLEDGE 



107 



In the application of the Eontgen rays to surgery in 

 France, the shadow photography has indicated that in a 

 case of bone disease the centre of the bone was affected, 

 and not the periosteum. The Kmits of tubercular affection 

 of bones of the hand have been ascertained, and an internal 

 ulceration of bone, lying beneath an ulceration of the skin, 

 has been discovered. In our own country Dr. -John 

 Macintyre, of Glasgow, has got remarkable shadow pictures 

 of the spinal column and ribs of a man. He finds that 

 the head is easily penetrated, and expects great things 

 from the application of Eontgen rays to surgery when a 

 more powerful source of these rays has been obtained. 



Experiments have been made by A. M. Bleile upon dogs 

 in order to determine the cause of death in electric shock. 

 The conclusion reached is that for a given animal in 

 normal condition as to health a definite amount of elec- 

 trical eni'r(jij will produce fatal results. It is thought that 

 the action of the electrical discharge is to contract the 

 arteries and increase the pressure of the blood, and that 

 death is due to inability on the part of the heart to sustain 

 the increased pressure of the blood so produced. Post- 

 mortem examinations seem to show that the passage of 

 the current does not cause any anatomical disintegration. 



The results of the use of antitoxic serum in the treat- 

 ment of diphtheria are clearly indicated by the report 

 recently issued as to the cases in the hospitals of the 

 Metropolitan Asylums Board. In 1894 there were 3042 

 cases and 902 deaths, the mortality per cent, being 29-6 ; 

 in 1895 the number of cases was 3529 and the number of 

 deaths 796, the percentage of fatal cases being 22-5. The 

 reduction in mortality of 7'1 per cent., occurring in the 

 second year referred to, must be attributed to antitoxin. 



Observations taken during the second half of the year 

 1895 by Tacchini, at the observatory of the Eoman College, 

 show that during this period sunspots have continued to 

 decrease, with a secondary minimum in November, when 

 spotless days were observed. The protuberances have 

 shown very little change during 1895. 



Moissan in France has analysed specimens of opium as 

 used by the Chinese, and finds that the smoke is formed 

 of volatile perfumes and a small quantity of morphine. It 

 is the latter which produces the phenomena sought by 

 opium smokers, and it is said that they do not appear to 

 find more ill effects from the practice than most tobacco- 

 smokers, provided that they use the preparation known as 

 chandu of the best quality. The commercial quality of 

 opium is, however, very different, and the inferior sorts 

 when decomposed by heat produce various poisonous com- 

 pounds. t.^ 



Some observations of the surface of the planet ^lars 

 recently made by Prof. Barnard with the Lick telescope 

 suggest that a possible change may take place in present 

 ideas as to what represents land and water on Mars. 

 The so-called " seas " did not appear to consist of seas 

 and oceans, but seemed to be exactly the reverse. They 

 were rich in markings which are compared to the aspect 

 of a mountainous country as seen from a great elevation. 

 On the "continental" regions irregular features represented 

 by delicate differences of shade were noticed, but no 

 straight sharp lines were seen on these surfaces. 



A plea for the increased use of imagination in science 

 was put forward by Prof. R. Meldola in a presidential 



address recently delivered to the Entomological Society of 

 London. That prince among experimental philosophers, 

 Michael Faraday, used to say, " Let us encourage ourselves 

 by a little more imagination prior to experiment" ; and 

 there is a tendency among men of science to-day to act 

 upon his advice. Science is organized knowledge, and no 

 mere collection of facts can constitute it. Observation and 

 experiment are primarily essential ; but we only become 

 scientific when we compare the facts accumulated, and use 

 the imagination to generaUze them and to guess at the 

 principles which they teach. The hypotheses thus arrived 

 at may be, and often are, wrong; nevertheless, real progress 

 only begins when facts are sought in relation to at least 

 the suggestion of a principle. 



Mark how extremely fi-uitful has been the late Mr. H. W. 

 Bates' explanation of the phenomena of mimicry and pro- 

 tective resemblance among butterflies and moths. While 

 pondering over the meaning of the remarkable superficial 

 resemblances among the butterflies of different groups 

 which he had collected in the Amazon Valley, it occurred 

 to him that the resemblance might be a real advantage in 

 some cases. There is, for instance, a beautiful group of 

 butterflies (the Heliconii) in the South American forests, 

 which, though they possess conspicuous colouration and fly 

 slowly and weakly, are not eaten by birds, and are therefore 

 very abundant. The reason they enjoy immunity fi-om 

 bu'ds appears to be that they possess a strong and offensive 

 odour, which is probably combined with a nauseous flavour. 

 But the curious thing is that certain butterflies of groups 

 which are not characterized by these disagreeable attributes, 

 are coloured in much the same way as their less edible 

 companions, so as to be commonly mistaken for them. 



Mr. Bates pointed out the protection from foes afforded 

 by such resemblances as these, and speculated on the 

 importance of adaptive colouration in the preservation of 

 species. The explanation which he sucfgested as the cause 

 of the phenomena gave vitality to what would otherwise 

 have been a disconnected and meaningless set of facts ; it 

 prompted further observation and experiment, and has 

 resulted in the accumulation of many new instances of the 

 same principle. The history of science furnishes numerous 

 similar cases where the use of the imagination has 

 stimulated enquiry and made for scientific progress, though 

 few investigators recognize them. The growth of a broader 

 feeling has, however, lately shown itself; to which state- 

 ment Prof. Meldola's remark, that " the philosophic 

 faculty is quite as powerful an agent in the advancement 

 of science as the gift of acquiring new knowledge by 

 observation and experiment," will bear witness. 



VARIABLE STARS. 



By Dr. A. Brester Jz. 



SINCE writing my article on red variables and Nova?, = 

 two remarkable investigations have been published 

 which are of the greatest importance for the de- 

 velopment of my theory, and especially in the case 

 of variable stars. 

 I have first to mention Mr. Alex. W. Roberts' study of 

 " close binary systems " in the November Number of the 



• iSee KjfOWLEDOK, December, 1895. The results of Messrs. Jewell, 

 Hiimplireys, and MoUler's investigations as to the effect of pressure on 

 tlie dii^phu'cnients of spectral lines give a new support to mv tlieorv that 

 tlie conipounil spc<'truni of a Xova does not pi-ove that it is caused bj 

 two oppositely moving bodies. Such a spectrum is much more easily 

 explained, 1 think, bv the great ditfercnccs in depths and corresponding 

 pressures at which the bright and dark lines originate. (Aslrop/ii/sical 

 Journal, February. ISiUi.) 



