In all life sciences there can be noted a marked trend toward an increased use of physical instrumentation. Calorimeters, which are instruments for measurements of heat quantities or heat effects, offer one approach in this respect.

The first recorded measurements of temperature changes in a muscle during contraction were made more than 120 years ago by means of a series of thermocouples connected to a galvanometer. The technique is the same today. In principle it is that of the adiabatic isoperibol calorimeter (Wadsö, 1970); heat generated by the system under study is shared with a thermal transducer, the electrical output of which is a measure of the consequent change of temperature and may be displayed by one of several devices. Most exponents in this field have to rely on home-produced assemblies and it is the intention of this article to consider the practical details of the separate components and, where possible, to discuss some of the various innovations which different workers have brought to the technique.