180 



♦ KNO^VLEDGE ♦ 



[June 1, 1887. 



THE JAPANESE MAGIC MIRROR. 



By Dr. E. F. Hutchinson. 



HAVE, at last, realised the longings of my boy- 

 hood, and am in possession of a Japanese magic 

 mirror. I have a hazy recollection of an 

 attempt — I think, by Sir D. Brewster — to solve 

 the mystery to the learned, but its effect on 

 me was to sink me deeper in the mire of 

 mystification. Even now, after repeated and 

 careful experiments, I am in statu, and can offer no expla- 

 nation of the optical mystery, nor can many to whom I have 

 exhibited it. If yon, or any of your readers, can enlighten 

 me, I shall be deeplj- obliged. 



I send you a rub of the back of the mirror, which 

 will help you to understand the magic. The body is 

 bronze, the face is said to be steel. It may be silvered, 



y 



X 



and, as far as I can make out, is quite plane. Your face is 

 reflected, as in any other mirror, though perhaps not so 

 clearly as in our own looking-glasses. 



On the reverse a goose or swan is stamped out in relief, 

 enveloped in its own plumage, and standing out about 

 •05 inches above the chequer- work of the ground. Now for 

 the mystery. Eefleet the sun with an ordinary plane mirror, 

 and you obtain a replica of the ftxce of the mirror on the 

 wall, .slightly smaller than the original. Reflect the magic 

 mii-ror, and you see, not the replica of the face, but the 

 image of the goose, surrounded by a glory of triangular 

 rays. A.nd, what is very strange, you do not see the image 

 you have on the reverse, but another one altogether; 

 thus, you see a dot on the beak, which is non-existent 

 in the image at the back, and you do not see the drop of 

 ink which you may place on the neck ; further, you do not 

 see the surrounding chequer-work, on the wall. Now, how 

 is this? I cannot explain. 



Another very remarkable phenomenon is witnessed on 

 handling the mirror in sunlight. You are distinctly aware 

 of tiro surfaces, and, if you move the mirror, the particles (?) 

 of the two surfaces pass each other in opposite directions, 

 like microscopic iridescent aerolites: one shown pa.ssing, 

 say, from north to south, and the other in the opposite 

 direction. This is very strange to see. Further, if you 

 look for a second at the surface in the sun, you cannot .see 

 the bii-d, hut your companion sees it on your face. The 

 natives to whom I have shown it are amazed, and regard it 

 as witchcraft {jiiih'i-r/a'ri). 



Another Japanese curio which I greatly value is a mag- 

 nificent crystal ball, about three inches in diameter — and this, 

 too, is great medicine to the natives, exhibiting, as it does, 

 a lovely miniature panorama of the surroundings ; but what 

 amazes them is, that, though cold as ice, they cannot hold it 

 in their hands in the sun, inasmuch as it burns like fury, 

 and I often have to save it from being dropped by them like 

 a hot potato. 



person, 

 r I as if 

 mirror 



C (PC = 



OUR PUZZLES (SOLUTIONS). 



rZZLE XXVIIL— AVhen anyone looks at his 



reflection in a mirror, he sees himself not as 



his friends see him, but with his left side doing 



duty as his right, and his right side doing duty 



as his left. But suppose AC, bc to represent 



the horizontal sections of two mirrors at right 



angles, r and l the right and left side of a 



p, facing the corner c. Then there will be an image 



behind mirror AC, and an image 1' r' as if behind the 



EC. But there wUl also be an image r' l' as if beyond 



cp'), and situate as shown. (The dotted line r»i nh, 



shows how the point l is seen from p in direction vm and 

 as if at l'.) This image appears to the person himself at p, 

 as he appears to his friends, the right .side h' fticing the 

 observer's left, and the left side facing the observer's right. 



It is not necessary to have mirrors such as AC, BC. Two 

 narrow strips of glass, supposed to be shown in section at 

 nc and mc, will suffice to show the observer his own 

 image, as if at ?'. In fact all that is necessary in such 

 cases is that a space should be mirrored near c so large that 

 if this mirrored part were an opening in the wall, the 

 whole of the observer's person set at p' would be visible 

 from p. 



Wherever the observer may go within the space BCA 

 he will see his image at c. If the two vertical mirrors 

 nc and mc, which are supposed to meet in a vertical line 

 at c, be set in rotation about a vertical axis through c, the 

 observer at p will see his image at c during one quarter of 

 each rotation ; and if the rotation is sufliciently rapid ho 

 will see his image apparently unmoving all the time. 



Puzzle XXIX. — It will be easily seen by the student 

 that if BC, AC are two mirrored sides of a room, the hori- 

 zontal ceiling of which is also a mirror, then an image will 

 further be formed as if beyond the corner above c, and 

 at the same distance beyond that corner that that corner 

 lies from p. This image will be inverted. (The student 

 will find it a useful exercise to draw lines corresponding to 

 p»i, 7)in, m, in the simpler case just dealt with, showing 

 how the various parts of the inverted image above p' will 

 be seen respectively on the ceiling, and on the two mirrored 

 walls CA, CB, close by the corner.) Thus, looking at any of 

 the top corners of the room, if walls and ceilings near those 

 corners are all mirrored, the observer will there see his face 

 (and figure if the mirror surfaces extend far enough) 

 inverted. He will see the like if he looks at the four lower 

 corners (similarly mirrored). 



Thus there will be eight inverted images at the eight 

 corners of the room, wherever the observer be situate inside 

 the room. 



Puzzle XXX. — If the twelve edges of the room (that 

 is the place-s where walls meet walls, floors, and ceilings) 

 be lined with mirrors to a suflicient breadth, the observer, 

 wherever he be situate, will see twelve images of himself 

 along the edges, viz. four upright in the four vertical edges, 

 and eight inverted in the edges bounding floor and ceiling. 

 He will further see eight inverted images at the eight angles 

 of the room. 



