86 General Notes. 
blows were struck by a hammer which struck with a known force, 
appended to an accurate recording apparatus. The extent of the 
jerk proved to be an index of the state of the nerves. The first 
series of experiments showed that the jerk obtained upon rising in 
the morning was small; that that given after breakfast was, on the 
average, higher than those at subsequent hours, and that it rese after 
each meal ; also, that the effect of muscular exercise was always to 
largely diminish its extent. Slight mental fatigue does not seem to 
affect the knee-jerk, while unusual mental fatigue produced an irri- 
tability which reinforced it. Irritation of the skin, voluntary 
movements, attention to unusual sounds, exciting mental work 
(such as the recitation of a stirring poem), music (especially of am 
emotional character), exciting dreams, all increased the extent of the 
knee-jerk. Violent respiratory movements also increased it, while 
a rise of temperature or a fall of the barometer diminished it, oppo- 
site meteorological conditions producing opposite results. A second 
series of experiments confirmed the results obtained by the first. 
ARCHZOLOGY AND ANTHROPOLOGY. 
THe Magic Mirror or CHINA AND JAPAN.—The magic 
mirror is the common toilet mirror or kKagemi in everyday use 1n 
Japan. It is a thin disk of cast bronze about eight inches in 
diameter, or of various sizes, and has a short handle cast with the 
piece. The plane side is amalgamated; on the back are repre- 
sentations in relief of bamboos, ships, storks, trees, etc., and gen- 
erally two large characters. oe 
The performance of this mirror has long excited great curiosity 
and interest, and there have been many ingenious conjectures as to 
the reason of the strange way of its reflection. The magic is that, 
when it is properly prepared and the sun’s rays caught upon 1t and 
reflected on a screen, the outlines of the characters and figures on 
the back show in the reflection. The figures appear lighter than 
the rest of the field, and not frequently with a sharp outline. 
Better results will be obtained if the mirror is slightly warmed, 
laid on its back on a perfectly flat surface, and briskly polish 
with acloth. Then, if the sun’s rays are caught upon it, at first 
in the reflection the figures cannot be seen, but they gradually 
appear and are permanent. In China its peculiarity has been long 
and well known, for it was spoken of with great admiration in the 
eleventh century by Tchin-Kouo, and the poet Kin-ma, celebrat 
it in verse. It is probably used as one of the very numerous 
agents of divination practiced there; and in passing, we note “er 
a mirror, the symbol of purity, is found in every Shinto temp! 
and shrine in Japan. The Chinese mirror has no handle; 1t 1$ 
held by cords passed through lugs at the back. 
