596 
Proceedings of the Royal Society 
me, it in a moment regained its right position. All this did not 
take half a minute. I went to bed and slept soundly, as indeed I 
always did through the whole course of the illness, except on the 
two or three occasions when an attempt to return to ordinary diet 
produced a disturbance of the digestive organs. Next morning, on 
:getting out of bed, I found that that movement of the body had 
produced a vertigo much more severe, and lasting a much longer 
time than either of those of the day before, and although it passed 
away on my remaining quiet for some time, every attempt to move 
set it up again. I accordingly went back to bed, and after lying 
quiet for a few minutes felt quite well ; but getting up was out of 
the question. To occupy myself I sent for the morning news- 
paper. "When it arrived I was lying on my right side, facing the 
window. To read it comfortably I had to turn round, so that the 
light should fall on it. I accordingly rolled myself over, and 
holding out the paper tried to read it. This, however, I could not 
do, the letters seemed to fly across the paper, and while I could see 
that it was print, and could make out the size of the letters, I could 
not distinguish one of them. This optical vertigo was not 
accompanied by any feeling of nausea or of insecurity. Reflecting 
upon what produced it, I thought I might undo it. If I rolled 
round to my right side again that might put it right, but then I 
wished to have the window behind me. I tried while keeping my 
body at rest, rolling my head quickly to the right, and then slowly 
back again, and found that an effectual remedy, and from that time, 
as long as I remained in bed or on the sofa, viz., about ten days, I 
could always neutralise an abnormal apparent rotation, by rotating 
the head about the axis of the apparent rotation, quickly in one 
sense, and then slowly back again. The sense in which the quick 
rotation had to be made was that in which surrounding bodies 
seemed to move. The first correction was sometimes too much, 
sometimes not enough; in such cases a second smaller correction 
was easily made. Day by day the intensity and duration of the 
vertigo became less. Once or twice a day, I made an experiment 
by making a whole rotation, and lying still to observe how long the 
apparent motion of external things continued. At last I found that 
I could walk about, not without some difficulty and feeling of in- 
security. This gradually diminished until a week or so before my 
return to ordinary food it was practically gone. 
