244 JOHN TYNDALL 
to indulge his propensity for climbing. It was not at 
all difficult to imagine him descended from a creature 
arboreal in its habits. He was very strong in the arms 
and fingers, while his weight, I should think, could 
hardly have exceeded one hundred and thirty, or at 
most one hundred and forty pounds. He would 
scamper up steep places like a cat. One of the 
Cunard captains told me that once when Tyndall 
crossed the ocean in his steamer, he had secured 
special permission to climb in the rigging, and seemed 
never so much at home as when slipping up between 
crosstrees or hanging upon a yard-arm. 
In 1867, on Faraday’s death, Tyndall succeeded him 
as Director of the Royal Institution, and soon after- 
ward began his remarkable series of inquiries into the 
cause of the changing colours of the ocean. This led 
to inquiries into the light of the sky, and the discovery 
that its blue colour is due to the reflection of certain 
rays of light from the tiny surfaces of countless par- 
ticles of matter floating in the atmosphere. This 
opened the door to studies of the organic matter held 
in suspension in the atmosphere, and to the relations 
between dust and disease, a most fruitful subject. In 
the course of these studies occurred the famous con- 
troversy on Spontaneous Generation, in which Dr. 
Bastian contended that sundry low forms of life de- 
tected in hermetically sealed flasks must have been 
newly generated from organizable materials within the 
flask; against which view Tyndall proved that no one 
has yet sealed a flask so hermetically that germs can- 
not enter. It was the same question which had been 
argued in France between Pouchet and Pasteur; but 
Tyndall’s researches strengthened the case against 
