45 



1. The pressure in the vacuous space is sensibly the same in all 

 parts. 



2. It is a matter of indifference in which direction the refrigerating 

 water flows in reference to the direction of the steam and condensed 

 water. 



3. The temperature of the vacuous space is sensibly equal in all its 

 parts. 



4. The resistance to conductivity must be attributed almost entirely 

 to the film of water in immediate contact with the inside and outside 

 surfaces of the tube, and is little influenced by the kind of metal of 

 which the tube is composed, or by its thickness up to the limits of 

 that of ordinary tubes. 



5. The conductivity increases up to a limit as the rapidity of the 

 stream of water is augmented. 



6. By the use of a spiral of wire to give a rotary motion of the 

 water in the concentric space, the conductivity is increased for the 

 same head of water. 



The author, in conclusion, gives an account of experiments with 

 atmospheric air as the refrigerating agent ; the conductivity is very 

 small in this case, and will probably prevent air being employed for 

 the condensation of steam except in very peculiar circumstances. 



IV. " Notice of Recent Scientific Researches carried on abroad/' 

 By the FOREIGN SECRETARY. 



During the last Session of the Royal Society the Council passed a 

 Resolution, That it should be one of the duties of the Foreign 

 Secretary to furnish the Society, from time to time, with early notice 

 of researches of special importance carried on abroad ; such notice to 

 be drawn up in the form of a short communication to the Society, 

 to be read as early as practicable at an Evening Meeting of the 

 Society, and published in the ' Proceedings.' In the time which 

 has since elapsed I have been only partially successful in obtaining 

 that cooperation without which it is scarcely possible to comply with 

 the instructions of the Council. 



