204 



KNOWLEDGE 



[September 1, 1898. 



and close by. Tiie star was regular in its movements, 

 but the seeing was only occasionally good. The maximum , 

 ■which evidently was a bright one, seems to have been 

 passed on or about the computed date for that phase, 

 March Hth. David Flanery. 



Memphis, Tenn., U.S.A., 

 23rd May, 1898. 



A THEORY OF EEFBACTION IN SUN-SPOTS. 

 To the Editors of Knowledge. 



Sirs, — I do not find that Mr. Jenkinson's objection, 

 that the refraction (illustrated in the August number of 

 Knowledge) would be destroyed by a blast from a pair 

 of bellows, has any foundation in fact. I enclose a photo- 

 graph which will show that a current of air has but little 

 effect on the refracted bottom. 



I have intentionally removed the " penny," as this has 

 but little to do with the discussion. 



It is, of course, true that a very slight ripple will often 

 destroy refraction, but this is from a cause that we can 

 hardly expect to find reproduced on the solar surface. In 

 rippled water the refraction ia often destroyed by the 

 reflection of the sky or of bright objects ; but if the surface 

 be shielded from bright rejections, refraction will suffer 

 but little. Arthur East. 



The report of the Select Committee on Museums of the 

 Science and Art Department has furnished abundance 

 of material for those who make it their business to criticise 

 the responsible agents of our State-aided institutions. 

 " The South Kensington King," the " Brompton Boilers," 

 the " Poor Relations' Benevolent Institution," and such 

 like sly insinuations have for many years been the only 

 encouragement which the heads of departments at South 

 Kensington have received from some quarters. " The 

 work has in innumerable instances," says one of our con- 

 temporaries, " been bad to the extent of dishonesty, and a 

 gross waste of public money. Indeed, so extravagant are 

 the faults proved against the department, that one can 

 hardly credit the truth of them." Even if all this be true, 

 the fact remains that the Department has accomplished an 

 incalculable amount of useful work, the mature fruit of 

 which still remains to be gathered in. 



A number of the cases of birds and their nests at the 

 Natural History Museum have been photographed by 

 Messrs. Newton & Co., and a series of coloured lantern 

 slides have thus been produced. Stuffed birds usually 

 look stiff and unnatural in a photograph, but the natural 

 surroundings in the cases photograph well, and the slides 

 are on the whole accurately coloured. 



Mental fatigue — the most characteristic of the ills that 

 flesh, or at all events civilised flesh, is heir to — has 

 during recent years been made the subject of carefal 

 scientific observation. Though there is still much to be 

 learnt respecting the factors influencing it, a very great 

 deal has been added to our knowledge of the conditions 

 attending its occurrence, and the means necessary for its 

 dissipation. The investigations regarding mental fatigue 

 naturally fall into two divisions. There is, first, the effect 

 of intellectual effort upon the physiological activities of the 

 body ; and, second, the result upon the mental powers 

 themselves. It has been fairly proved that all intellectual 



worli has an immediate effect upon the physiological state 

 of tlie various bodily organs. Thus, the earliest result of 

 the mind's activity is to quicken the heart beat, though 

 after half-an-hour a distinct slackening follows. This 

 is naturally accompanied by an increased blood pressure 

 on the brain. Similarly, respiration is quickened, though 

 the inspirations and expirations of air are not, individually, 

 as vigorous. The amount of tissue used up in the body 

 increases, too, as is shown by the larger absorption of 

 oxygen from the air, and the increased expiration of waste 

 product in the form of carbon dioxide. Such increased 

 wasting away of the material of the body has been found, 

 as one would have expected, to carry with it an increase in 

 bodUy temperature. A particularly important relation has 

 been made out between intellectual and muscular effort. 

 While a brief mental exercise of fifteen minutes or less 

 seems to increase the momentarily available muscular 

 energy, a longer mental exertion distinctly decreases it, . 

 though when it is accompanied by emotional excitement 

 this mind work may not be followed by the enfeebling of 

 the muscles until much later. Observations made in a 

 French school show that the amount of bread consumed by 

 the pupils, who were always allowed to have just as much 

 as they wanted, decreased with fair regularity until the 

 minimum was reached in July. This is interpreted to 

 mean that there is a gradual decrease in vitality as the 

 result of continued school work. Many other results of less 

 popular interest have been obtained and will be found 

 described in an excellent volume on mental fatigue, by 

 Professors Binet and Henri, recently published in Paris. 



Many people believe that soon after death a peculiar 

 smell arises from the body. " There ia death in the 

 house," old women will say. So, too, it is well known 

 that in some coimtries ravens appear, oftentimes in large 

 numbers, almost immediately animals have expired. It ia 

 eaay to explain all such phenomena by changes due to 

 decay of the body ; but the smell before death, which ia 

 referred to as odor mortis, is not so easily understood. 

 This " death smell " attracts several species of flies to the 

 dying in certain seasons, and the approach of death in a 

 human being or animal, if it occurs at a time of the year 

 when these insects are in active life, is said by some to be 

 unmistakably heralded by the determined manner in 

 which such fliea settle on the skin, especially in the region 

 of the nostrils. According to many authorities the smell 

 is unappreciable to average nasal organs, though not a few 

 trained observers are without doubt of its existence. Of 

 numerous cases which have recently been put on record in 

 the Britiuli Medical Journal, one or two may be referred to 

 here, as they provide sufficient ground for further investi- 

 gation. An apparently strong, healthy nurse was suffering 

 from a severe attack of typhoid, and towards the end of 

 the first week a peculiarly heavy odour was noticed about 

 the patient by the doctor in attendance, and since he had 

 noticed a similar smell in previous fatal cases he felt 

 anxious. Shortly after the odour had been detected the 

 nurse developed other symptoms and died. Another 

 physician records that having remarked the smell in the 

 case of a child, who otberwise did not appear to be 

 seriously ill, he regarded it as a sign of most unfavourable 

 import, and sought a consultation. The consultant 

 thought there was no cause for anxiety, yet the child 

 died within forty-eight hours. These, and other cases 

 described by medical men, certainly give ground for the 

 belief that, in some cases at least, the approach of death 

 ia heralded by a strange odour, though it ia diflicult to 

 understand exactly the cause of its occurrence. 



