1878.] 



The Magic Mirror of Japan. 



127 



although, one clause of a sentence in it, read by itself, might be sup- 

 posed to do so. The passage is to be found in their work at p. 286. 

 They begin by saying, that their experimental observations detailed in 

 their previous pages " prove that even in a perfectly calm day there is a 

 strong resistance to the motion of the water at the surface as well as 

 at the bottom," and that this resistance at the surface " is not wholly 

 or even mainly caused by friction against the air." They go on to 

 say: — " One important cause of this resistance is believed to be the 

 loss of living force, arising from, upward currents or transmitted 

 motion occasioned by irregularities at the bottom. This loss is greater 

 at the surface than near it. The experiment of transmitted motion 

 through a series of ivory balls illustrates this effect. It is likewise 

 illustrated on a large scale by the collision of two trains of cars on a 

 railway, in which case it has been observed that the cars at the head 

 of the train are the most injured and thrown the farthest from the 

 track ; those at the end of the train are next in order of injury and 

 disturbance ; while those in the middle of the train are but little 

 injured or disturbed. Other causes may and probably do exist, but 

 their investigation has, fortunately, more of scientific interest than 

 practical value. For all general purposes it may be assumed that 

 there is a resistance at the surface, of the same order or nature as that 

 which exists at the bottom." 



Now although this passage does contain the words " arising from 

 upward currents or transmitted motion occasioned by irregularities at 

 the bottom" yet the illustrations, by means of the series of ivory 

 bails, and of the collision of railway trains, show that the authors 

 attribute to those words no clear and correct meaning, but, on the 

 contrary, I would say they put forward quite a false view of the 

 actions going on. Besides I myself do not admit that, except from the 

 ail", there is a resistance at the surface. According to my supposition 

 the already resisted and retarded bottom water comes to the surface 

 and spreads out there, but receives no new resistance there, and on 

 the contrary receives acceleration from gravity in running down hill. 



II. " The Magic Mirror of Japan." Part I. By Professors 

 W. E. Ayrton and John Perry, of the Imperial College of 

 Engineering, Japan. Communicated by William Spottis- 

 woode, Esq., M.A. S Treas. R.S., &c, &c. Received October 

 2, 1878. 



The Japanese mirror must, from three points of view, attract the 

 notice of foreigners sojourning in that country — its prominence in the 

 temples, the important feature it forms in the limited furniture of a 

 Japanese household, and the wonderful property (which has apparently 



