Telescope 30 seconds. 4. Double image prism 15 seconds. 5. Naked eye 10 seconds. 6. Finder or binocular 20 seconds. 7. Telescope 20 seconds. 7. Telescope 20 seconds. 7. Telescope 20 seconds. 7. Telescope 20 seconds. 7. Telescope 20 seconds. 7. Telescope 20 seconds. 8. Observe retreat of the furnace F the _vis viva_ the waves disappear, but in the surrounding aether undulations which speed through it a power.