370 Proceedings of the Royal Society 
are the apparent intensities of the red and bine parts. But, if ^th 
only of the light from the flame is scattered from white paper; the 
intensities of the red and blue rays, when the paper is examined, 
are 
H-L 
71 
.... (3) 
. . . . 
71 
.... (4). 
Now, it is quite possible that while (1) is greater than (2), (4) 
should be greater than (3). Hence the light seen from the gas- 
flame has, on the whole, a red tinge, while that of the paper has a 
blue tinge, exactly as is seen to be the case. 
I hope that this attempt at approximating to a better knowledge 
of some theoretically important facts will be of some interest to the 
Society, and that the meagre nature of our data will be sufficient 
apology for the small advance I have been able to make. 
4. On the Semicircular Canals of the Internal Ear. 
By Professor Crum Brown. 
( Abstract .) 
The author had laid before the Society, on the 19th January, a 
preliminary note containing an outline of a theory of the function 
of the semicircular canals of the internal ear. In that note it was 
stated that the six semicircular canals form three pairs — the mem- 
bers of each pair being parallel, and having their ampullae at 
opposite ends. In this paper the author communicates the results 
of measurements of the position of the bony canals in a large 
number of animals. 
The only manner in which, assuming bilateral symmetry, the 
canals can be arranged in parallel pairs, with the ampullae at the 
opposite ends, is as follows: — In each ear, one canal at right angles 
to the mesial plane, and the two others making equal angles with the 
mesial plane. Calling the canals of the one ear a , b , c, and those of 
the other ear a', b', c ' ; a and a', b and c', c and b' are the three pairs ; 
a and a' are coplanar, b is parallel to c' and c to V . The measure- 
