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- haemoglobin is like a four-seater car or an unstable four-man boat
- Halley's comet has a wanton tail
- handling editor
- hard core
- heavens resemble a luxuriant garden
- heavy bodies endeavour to reach the earth
- heavy stars have a sort of onion skin structure
- Helmholtz, Hermann von
- hermeneutics
- heuristic
- HF loves the idea of donating a fluorine to SbF5
- history conjecture
- Holden, Alan
- Hooke, Robert
- hospital processed lithium like a small outback mining town
- Hoyle, Fred
- human development is like a lightbulb giving rise to a massive office block
- Hume, David
- hungry nuclei grab neutrons
- hunt for mutation is like searching 65 freight cars for one bad orange
- hybrid conception
- hydrogen bonds are like those you have with colleagues
- hypotheses may be hatched by theories of other species
- hypothesis-observation is like chicken-egg