542 



NATURE 



\April lo, 1879 



the pressure of the rod than the thinner, and so would be 

 made less convex, or even they might not spring back, on 

 the withdrawal of the rod and so remain actually concave. 

 Again, since we find that scraping the face of the mirror is 

 the way in which it is made convex, and the back therefore 

 concave, we might conclude that a deep scratch on the 

 back would made the back convex and the face slightly 

 concave. Such a concavity would, as we have proved, 

 explain the phenomenon of the bright line appearing in 

 the reflection of sunlight on the screen, which was ob- 

 served by Prof. Atkinson to correspond with the scratch 

 on the back. 



After the scratches produced by the megebo are removed 

 the mirror is polished with whetstones and then with 

 charcoal. The face now becomes fairly smooth, but it 

 still generally contains some few cavities ; these the 

 maker fills up from a stock of copper balls of various 

 sizes which he has at hand. (It was probably the presence 

 of these bits of copper that led Ou-tseu-hing to believe 

 that the explanation of the cause of the magic mirrors 

 was the inlaying of different metals.) The face of the 

 mirror is finally rubbed over with a mercury amalgam 

 containing 50 per cent of tin, by means of a small straw 

 brush or the hand. 



The lecturer then referred to the various metal mix- 

 tures employed by the Japanese in making their mirrors, 

 the best being composed of 75 per cent, of copper, 23 of 

 tin, and 2 per cent, of a natural sulphide of lead and 

 antimony. 



Although the Japanese have paid no attention to the 

 magic mirror, which has created such interest in Europe, 

 they have, in connection with their priestcraft, employed 

 mirrors on the surface of which, if looked at obliquely, could 

 be seen the faces of saints, but which were not in any way 

 connected with the pattern on the back of the mirror. [Pho- 

 tographs of such mirrors were projected on to the screen.] 

 The lecturer also exhibited two mirrors of this kind which 

 he had had made in consequence of the belief expressed by 

 one of the Japanese mirror-makers that the phenomenon of 

 the so-called magic mirrors was produced by chemical 

 action on the surface. But the result of the experiment 

 had been that if the face of a mirror which had been 

 chemically acted on was polished until every trace of the 

 marks disappeared for direct or oblique vision, then they 

 also disappeared in the image produced by reflecting a 

 beam of light on to a screen, and consequently that it did 

 not seem possible, as far as his experiments had gone, to 

 produce, by means of chemical action on the surface, a 

 mirror fulfilling all the conditions of the magic mirror. 



He concluded by saying : " It appears, then, contrary 

 to what is commonly believed, that the magic of the 

 Eastern mirror results from no subtle trick on the 

 part of the maker, from no inlaying of other metals or 

 hardening of portions by stamping, but merely arises 

 from the natural property possessed by certain thin 

 bronze of buckling under a bending stress, so as to remain 

 strained in the opposite directions after the stress is re- 

 moved. And this stress is applied partly by the distorting 

 rod, and partly by the subsequent polishing, which, in an 

 exactly similar way, tends to make the thinner parts more 

 convex than the thicker." 



GEOGRAPHICAL NOTES 



The April number of Petermann's Mittheilungen con- 

 tains a paper of considerable geographical and geological 

 value by Dr. Edmund Naumann, on the Plain of Yedo, 

 Japan ; it is accompanied by several illustrations and a 

 fine map. Lieut. Onatzewich's account of his cruise in 

 the clipper Wssadnik to the north of Behring Strait in 

 1876, is well timed in connection with the Vegds sojourn 

 in that region. Dr. von Scherzer contributes an interest- 

 ing paper on anthropometry, and Capt. Johannesen de- 

 scribes the voyage of the Le7ta from the mouth of the 



River Lena to Jakutsk. The monthly summary contains, 

 as usual, many interesting items. 



The February number of the Bulletin of the Paris 

 Society gives M. Savorgnan de Brazza's paper on his 

 Ogowd expedition, the results of which we have already 

 stated. A valuable and detailed notice of Dalmatia is 

 contributed by M. de Sainte-Marie, and the number con- 

 tains the recent correspondence of Dr. Crevaux from 

 Guiana, referred to last week. The Nouvelles are 

 continued. 



As we stated last week, though M. Soleillet has got so 

 far on his journey to Timbuktu, it must not be forgotten 

 that some fifteen years ago Lieut. Mage and Dr. Quintin 

 reached the same place, and that after being detained as 

 prisoners for eighteen months by the present Sultan 

 Ahmadu, they were refused permission to embark on the 

 Niger, and compelled to return to the coast re infectd. 

 Indeed, just as we go to press we learn that a telegram 

 sent to the French Societe de Gdographie announces that 

 the progress of M. Soleillet has been cut short. He was 

 stopped by Ahmadu, the Emperor of Segou under the 

 pretence that the roads are insecure in the north of his 

 government. M. Soleillet has returned to St. Louis. 



With reference to our note last week (p. 516) on the 

 Conference in connection with the Inter-oceanic Canal, 

 M. Maunoir, Secretary of the Paris Geographical Society, 

 writes us that the Conference is to be held on May 19 

 under the auspices of that Society and not of the Society 

 of Commercial Geography. The Congress, M. Maunoir 

 writes, will not have any particular project in view, but 

 will give an impartial hearing to the various projects 

 brought before it. The various solutions of the questions 

 proposed will be propounded by their authors, and, if 

 deemed advisable, the Congress may in the end give its 

 approval of one or other of the projects. 



The April number of the Church Missionary Intelli- 

 gencer states that letters have been received from the 

 missionary reinforcements who are travelling up the Nile 

 to join the Nyanza expedition. They only reached Lado 

 opposite Gondokoro, on October 10 ; after three weeks 

 stay at that Egyptian station they reached Regiaf on 

 November 7. The cause of delay, we are told, has been 

 that the Nile has been unusually high, and the immense 

 quantity of water loosened great masses of reeds and 

 papyrus which formed floating islands and blocked up the 

 river, besides which, owing to a deficiency of fuel between 

 Khartoum and Lado, they remained fast bound during 

 the whole month of September some distance south of 

 Sobat, and the missionaries saw no living beings (besides 

 the men on board) but "pelicans, fishes, and a white- 

 headed eagle or two." 



Annexed to the recently issued report of Her 

 Majesty's Consul on the newly-opened port of Wenchow, 

 is a very interesting map of the three Chinese provinces 

 of Chekiang, Fukien, and Kiangsi, showing the means of 

 communication by land and water between the principal 

 cities and districts. The object of the map is more espe- 

 cially to point out the position of Wenchow as regards 

 some of the most important districts in these provinces, 

 the names of which with their products are given. 



Garibaldi has snubbed the Italian New Guinea expe- 

 dition, so that it may now be regarded as nipped in the 

 bud. 



The collection of funds instituted by the Dutch Central 

 Committee for Arctic Exploration for the renewed out- 

 fitting of the Willem Barents, which vessel is shortly 

 to start on another expedition of some eignteen months' 

 duration, is progressing so favourably that it may be 

 reasonably expected that the 50,000 florins which are 

 required for the expedition will soon be completely 

 subscribed. 



