Volume 12 in this distinguished series starts with a chapter on high temperature superconductivity. The chapter is of general interest, giving a historical perspective of the various speculations in the past on the possibility of such superconductors and the possible mechanisms for the superconductivity in the recently discovered materials. Other chapters illustrate the wide range of physics which are more usual low temperature topics, such as spin polarized 3 He gas and the Kapitza thermal boundary resistance at mainly millikelvin temperatures. Topics from neighbouring fields such as metal physics and applications of low-temperature physics are dealt with in chapters on charge density waves and multi-SQUID devices and their applications.