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3. an apparatus consisting of a tube attached to a set of mirrors or prisms, by which an observer (typically in a submerged submarine or behind a high obstacle) can see things that are otherwise out of sight.
4. a device used to measure temperature
7. a metric unit of measurement equal to 1,000 metres
12. the branch of biology that deals with the relations of organisms to one another and to their physical surroundings
16. the branch of mathematics concerned with the properties and relations of points, lines, surfaces, solids, and higher dimensional analogues
17. an optical instrument used for viewing very small objects
18. an instrument measuring atmospheric pressure
20. an instrument on a vehicle's dashboard indicating its speed
21. a vacuum flask
22. the study of the physical features of the earth and its atmosphere
23. a straight line passing from side to side through the centre of a body or figure, especially a circle or sphere

1. a device that automatically regulates temperature
2. the study of myths
5. one thousandth of a metre
6. an optical instrument designed to make distant objects appear nearer
8. a medical instrument for listening to the action of someone's heart or breathing
9. the outermost parts or boundary of an area or object
10. relating to or produced by the internal heat of the earth
11. the science which deals with the physical structure and substance of the earth
13. a small cavity in rock lined with crystals or other mineral matter
14. the study of the origin of words
15. the scientific study of the behaviour, structure, physiology, classification, and distribution of animals
19. a forecast of a person's future, based on the relative positions of the stars and planets at the time of that person's birth