Item 5 - Notes and calculations on heat

Found with correspondence between Huia Onslow and J. Donovan, and probably relates to Onslow's attempts to answer Donovan's queries.

Includes headings 'Determination of H𝑥', 'Methods of determining H', 'Methods of determining quantities in (2)', 'The Human body as a Heat Engine per H', 'Balance Sheet', 'The efficiency of a machine as a heat engine per hour'.