DR. HUBERT AIRY OH A DISTINCT FORM OF TRANSIENT 1IEMIOPSIA. 261 
I cannot remember any instance in which the cloucl, springing up and spreading on 
one side of the field, has ever transgressed the vertical median line. I believe it has 
never done so, but I cannot speak positively on the point. (In Sir John Herschel’s 
case it is distinctly stated that the shadowy intruder swept over the whole field from 
left to right; and Tyrrell speaks of instances in which the blindness “increases so as 
to extend over the whole field of vision.”) 
Colour . — When viewed in the dark, the general hue of the self-luminous cloud is 
yellowish-white. The casual gleams with which it is adorned are, in order of frequency, 
red and blue, yellow, green, orange. They seem to belong to the bright lines of the 
margin, but are less definite, and appear sometimes to spread over a wider space ; but 
it is by no means easy to determine the exact relations of the various tracts of light and 
shade in the turbulence and trembling that prevail ; especially when it is borne in mind 
that in order to do so the attention must leave the centre of sight and by effort of will 
transfer itself to a point 20° or 30° or 40° removed from the centre. 
Sequelce . — The headache has been very slight in some cases ; but generally is very 
oppressive, with some degree of “ eyeball pain.” The nausea, usually slight, was sufficient 
to produce vomiting on one occasion. I have never experienced any affection of speech 
with or after these attacks. But lately they have been followed by a slight disturbance 
of hearing, in which external sounds gave rise to a momentary ‘rumbling’ in my ears. 
I have once or twice tried to relieve the headache by the plan which M. Dufour 
recommends — abundant application of cold water to head and face, — but without 
success. The action of an emetic in no way prevented the cephalalgia. Indeed I have 
little reason to regard any gastric derangement as the cause of the affection in my case ; 
and though the stomach is secondarily affected, yet the primary disease is not easily 
reached by simply acting on the stomach. 
In one case (among my friends) with which I am well acquainted, these attacks have 
been very frequent from an early age till middle life. The bastioned outline is a striking 
feature in this case ; but I am not able to say whether the blindness does or does not 
transgress the median vertical line of the field of view. It is always spoken of as ‘ half- 
blindness.’ Formerly the attendant headache used to be very severe, accompanied with 
prolonged vomiting. Latterly the visual affection has been more oppressive than the 
headache, and its advent greatly dreaded. Sometimes the speech is affected, and the 
memory at the same time ; on one occasion the mouth was seen to be drawn to one side. 
The cause has been easily recognized in previous anxiety and mental distress, trouble- 
some letter-writing, and the like. 
In another case the phenomena are much less definite. The first sign of the approach 
of an attack is a half-puzzled suspicion that the eye does not see all it ought, and it 
requires some gazing at surrounding objects to settle the doubt. Once it began with 
mdccclxx. 2 M 
