remarked, with an air of mature conviction, that the
weather was hot for the time of year. 

"Very," answered the stranger shortly, hesitated a
second, and added in a colourless tone, "I can't sleep."  

Isbister stopped abruptly.  "No?" was all he said,
but his bearing conveyed his helpful impulse.   

"It may sound incredible," said the stranger, turning
weary eyes to Isbister's face and emphasizing his
words with a languid hand, "but I have had no sleep
--- no sleep at all for six nights." 

"Had advice?" 

"Yes.  Bad advice for the most part.  Drugs.  My
nervous system...  .  They are all very well for
the run of people.  It's hard to explain.  I dare not
take .  .  .  sufficiently powerful drugs."