Bullard's first work on marine heat flow was at the Scripps Institution of Oceanography in 1949 (see Section C. passim but especially C.12-C.14). The continuation of his collaboration with A.E Maxwell at Scripps and with E.R Niblett at Toronto can be seen in correspondence at D.406, D.415.
Most of the material below is concerned with the construction of apparatus, its use during sea-going expeditions and the analysis of results 1950-58, when Bullard was at the National Physical Laboratory and then at Cambridge.
For logs and accounts of expeditions on R.R.S 'Discovery II' during and after this period, see Section B.
Titles and descriptions on the folders have been retained and appear in inverted commas (not always in Bullard's hand); the contents of bulky folders have sometimes been sub-divided for ease of reference, and very decrepit folders have been discarded.