202 



NA TURE 



{Dec. 29, 1887 



comir.on among the peasants. Such are clearly traceable to the 

 national food, gofio, which in this island is made of Indian 

 corn. 



For phthisis the Canary Islands have been proved of inestim- 

 able value, and therefore on this point nothing more need be 

 said. The temi^erature throughout the year, by day and by 

 night, varies exceedingly little. In my recently-published work 

 on these islands I have gone so fully into this question that I 

 need not recapitulate it here. 



I should not have thus ventured to trouble you had I not been 

 asked by some leading members of the medical profession to 

 summarize the facts, bearing upon diseases, scattered through the 

 pages of my book and to add thereto others which I had deemed 

 unsuitable for the general reader. Olivia M. Stone. 



II Sheffield Gardens, Kensington, W. , December 14. 



The Ffynnon Beuno and Cae Gwyn Caves. 



Mr. Smith has entirely failed to substantiate the 

 statement made by him in his letter of December i (p. 105) 

 concerning the drift over the entrance of the Cae Gwyn 

 Cave, which is 20 feet in thickness and full of ice-scratched 

 boulders, many of large size ; therefore I need only say in reply that 

 the Geological Surveyors who surveyed this district have examined 

 the section and have had no hesitation whatever in classifying the 

 deposits in the section with the Glacial beds of the area. In 

 regard to the age of river-drift implements as compared with 

 those found in the cavern, which are identical with the imple- 

 ments found in Kent's cavern and the French caves, I need 

 only quote the remarks of M. Lartet (" Reliquiae Aquitanicje," 

 p. 9): — " If some are inclined to attribute to the works of 

 human industry found in the 'Diluvium' or 'Drift' a date more 

 ancient than to those occurring in caves with a similar association 

 of animal remains, we are obliged to remark that such a pro- 

 position, expressed as a systematic generalization, is not justifiable 

 in any point of view." . , . "Caves were in truth the first 

 shelter which primitive man would choose, whether driven by 

 instinct or determined by reason." 



When Mr. Smith calls the implements found in the gravels at 

 Mildenhall, Neolithic, which others claim to be Paleolithic, and 

 one most eminent authority to be pre-Glacial, I am perfectly 

 justified in saying that the classification of such implements, 

 as defined by Mr. Smith, has no chronological value, and 

 therefore I do not think that anyone is likely to be convinced by 

 his arguments when he is " content to resist the idea of the pre- 

 Glacial age of these caves on purely archaeological grounds." 



Henry Hicks. 



Hendon, December 23. 



Distorted Earth Shadows in Eclipses. 



With reference to the peculiar appearance of the earth's 

 shadow in the lunar eclipse of August 3 of this year, and noted by 

 " H. H." and " M. C." (see Nature, vol, xxxvi. pp. 367 and 

 413), it may be of interest to record a similar distortion observed 

 by Capt. A. E. Barlow, on the s.s. Nizam, at Suez, on August 

 23, 1877. The following entry appears in his meteorological 

 log :— 



"The eclipse of August 23. The moon as seen at mid- 

 night at Suez. Weather fine starlight. A few cir.-c. (amount 3) 

 travelling from northward." 



The shadow was irregular and jagged as in "M.C.'s" 

 description, Henry Toynbee, 



Marine Superintendent. 



Meteorological Office, December 22. 



DR. BALFOUR STEWART, F.R.S. 



T N the genial Manchester Professor the scientific world 

 ■*• has lost not only an excellent teacher of physics but 

 one of its ablest and most original investigators. He was 

 trained according to the best methods of the last genera- 

 tion of experimentalists, in which scrupulous accuracy 

 was constantly associated with genuine scientific honesty. 

 Men such as he was are never numerous ; but they are 

 the true leaders of scientific progress : — directly, by their 

 own contributions ; indirectly, though (with rare excep- 



tions) even more substantially, by handing on to their 

 students the choicest traditions of a past age, mellowed 

 by time and enriched from the experience of the present. 

 The name of Stewart will long be remembered for more 

 than one striking addition to our knowledge, but his 

 patient and reverent spirit will continue to impress for 

 good the minds and the work of all who have come under 

 its influence. 



He was born in Edinburgh, on November i, 1828, so 

 that he had entered his sixtieth year. He studied for a 

 short time in each of the Universities of St. Andrews and 

 Edinburgh, and began practical life in a mercantile office. 

 In the course of a business voyage to Australia his par- 

 ticular taste for physical science developed itself, and his 

 first published papers : — " On the adaptation of the eye 

 to different rays," and " On the influence of gravity on 

 the physical condition of the Moon's surface" : — appeared 

 in the Transactions of the Physical Society of Victoria in 

 1855. On his return he gave up business for science, and 

 resumed study under Kelland and Forbes, to the latter of 

 whom he soon became Assistant. In this capacity he had 

 much to do with the teaching of Natural Philosophy on 

 occasions when Forbes was temporarily disabled by his 

 broken health. During this period, in 1858, Stewart was 

 led to his well-known extension of Prevost's Law of 

 Exchanges, a most remarkable and important contribu- 

 tion to the theory of Radiation. He seems to have been 

 the first even to suggest, from a scientific stand-point, that 

 radiation is not a mere surface phenomenon. With the 

 aid of Forbes' apparatus, then perhaps unequalled in any 

 British University, he fully demonstrated the truth of the 

 conclusions to which he had been led by theory ; and the 

 award of the Rumford Medal by the Royal Society, some 

 years later, showed that his work had been estimated at 

 its true value, at least in the scientific world. In fact his 

 proof of the necessary equality between the radiating and 

 the absorbing powers of every substance (when divested 

 of some of the unnecessary excrescences which often mask 

 the real merit of the earlier writings of a young author) 

 remains to this day the simplest, and therefore the most 

 convincing, that has yet been given. 



Radiant Heat was, justly, one of Professor Forbes' pet 

 subjects, and was therefore brought very prominently 

 before his Assistant. Another was Meteorology, and to 

 this Stewart devoted himself with such enthusiasm and 

 success that in 1859 he was appointed Director of the 

 Kew Observatory. How, for eleven years, he there main- 

 tained and improved upon the memorable labours of 

 Ronalds and Welsh needs only to be mentioned here : — 

 it will be found in detail in the Reports of the British 

 Association. Every species of inquiry which had to be 

 carried out at Kew : — whether it consisted in the testing 

 of Thermometers, Sextants, Pendulums, Aneroids, or 

 Dipping-Needles, the recording of Atmospheric Electri- 

 city, the determination of the Freezing-Point of Mercury 

 or the Melting-Point of Paraffin, or the careful study of 

 the peculiarities of the Air-Thermometer : — received the 

 benefit of his valuable suggestions and was carried out 

 with his scrupulous accuracy. 



About twenty years ago Stewart met with a frightful 

 railway accident, from the effects of which he did not 

 fully recover. He was permanently lamed, and sustained 

 severe injury to his constitution. From the vigorous 

 activity of the prime of life he passed, in a few months, 

 to grey-headed old age. But his characteristic patience 

 was unrufiled, and his intellect unimpaired. 



His career as Professor of Physics in the Owens Col- 

 lege has been, since his appointment in 1870, brilliantly 

 successful. It has led to the production of an excellent 

 treatise on Practical Physics, in which every necessary 

 detail is given with masterly precision, and which con- 

 tains (what is even more valuable, and could only have 

 been secured to the world by such a publication) the 

 matured convictions of a thorough experimenter as to 



