318 JAMES CLERK MAXWELL. [CHAP. XI. 



which ran the whole length of the house. When ex- 

 perimenting at the window with the colour-box (which 

 was painted black, and nearly eight feet long), he 

 excited the wonder of his neighbours, who thought him 

 mad to spend so many hours in staring into a coffin. 

 This was also the scene of his well-known experiments 

 on the viscosity of gases at different pressures and 

 temperatures. For some days a large fire was kept up 

 in the room, though it was in the midst of very hot 

 weather. Kettles were kept on the fire, and large 

 quantities of steam allowed to flow into the room. 

 Mrs. Maxwell acted as stoker, which was very ex- 

 hausting work when maintained for several consecu- 

 tive hours. After this the room was kept cool, for 

 subsequent experiments, by the employment of a con- 

 siderable amount of ice. 



During Maxwell's residence in London his brother- 

 in-law, the Rev. Donald Dewar, came and stayed in his 

 house in order to undergo a painful operation at the 

 hands of Sir James Ferguson. Maxwell gave up the 

 ground floor of his house to Mr. Dewar and his nurse. 

 He himself, meanwhile, used to take his meals in a very 

 small back room, where frequently he breakfasted (on 

 porridge) on his knees, because there was no room for 

 another chair at the table. Maxwell acted frequently 

 in the capacity of nurse to Mr. Dewar, who would 

 always look out anxiously for his return from college, 

 and whose face would light up with a smile of plea- 

 sure and relief when he saw him coming, because he 

 said he knew he should be comfortable when Maxwell 

 returned. 



