y. B. S. Haldane 105 



carried for the purpose of proving whether the air were 

 breathable or not. On another occasion Haldane accom- 

 panied his father down a Cornish tin-mine. They were 

 crossing a plank spanning an abyss when suddenly their 

 light went out. 



" Luckily/' said Mr Haldane drily, " one has no sensa- 

 tion of giddiness in the dark." 



An experiment in which he took part at a tender age 

 was one which involved his being shut up in an air-tight 

 box, a sort of coffin, that left only his head free. This was 

 done with the object of getting a quantitative record of 

 expansion when the subject was breathing certain mix- 

 tures of gas. 



An adventure which amused him considerably was a 

 short voyage in a French ship from Tilbury to Dunkirk. 

 The vessel was full of rats ; and the French authorities, 

 who were in the throes of a plague scare, had asked 

 Haldane Senior to test a new system for gassing rats. 

 The forecastle was hermetically closed and the gas turned 

 on. When it was opened again J. B. S. and a friend of his 

 own age amused themselves by plunging into the still 

 poisonous air and seeing who could collect most dead rats 

 and cockroaches before choking. 



J. B. S. Haldane has persisted in his habit of experi- 

 menting on himself. During the War he was employed 

 on problems arising out of the ventilation of submarines. 

 On one occasion he and a companion were voluntarily 

 imprisoned in a steel cylinder seven feet high and five in 

 diameter. The manhole was then closed and screwed 

 down, and an engine began to suck out the air through a 

 pipe. The air inside became very cold and filled with 

 mist. In five minutes it had reached a pressure corre- 

 sponding to that of a mountain-top twenty-two thousand 

 feet high. Mr Haldane began to observe his own 

 symptoms. He was breathing rapidly and deeply, and 

 his pulse was one hundred and ten, but the breathing 



